So looking at a few Osprey packs going to be used for work and camping with the family. I work for the National parks at Big Bend park part of my job is to hike the trails two times a week trail can be 1 mile round trip to 14 miles or more. This pack is also going to carry my medical gear what I'm allowed to carry now and what I will carry when I get my EMT. This is also going to be my search and rescue pack its going to be used for just about everything. What I'm wanting to know is how large of a pack do you really need? I'm looking at the Aether AG packs 85,70,60 liter packs one thing I do like is that they have a day pack on them also.

So price is not an issue only $40 between the smallest and largest pack. Issue is this I do not want a pack that is so big that it looks sloppy if its not full but also want a size that can carry what I need. Not sure how this pack looks half full or with a little in it maybe someone can help or give advice on that to me. Yet I do not want to go to small I know I'm the person who on camping trips carries most of the gear a lot of the time the wife throws her stuff in my pack. The 50L Kelty Redwing my wife has is OK for weekend car camping think i need more then that! So like to hear your advice!

That's a tough call and depends heavily on the location, season, and activities.  Being SAR, you'll likely have a heavier and bulkier load.  Remember that for packs, don't just focus on their capacity, focus on the comfort range for actual weight.  I love my ULA Circuit pack which is my three-season backpacking bag, but I have to take care not to exceed the weight limits (about 30-35 pounds) or the comfort level really starts to drop.  I don't like floppy packs and I don't like hanging a ton of stuff on the outside of my pack...which means I have more than a few packs  Functional compression is key to keeping a larger pack from flopping around when not fully loaded and not too many do this very well.

I'm seriously looking at Seek Outside packs solely because I want a pack that is relatively light, but can haul heavier loads (most of their packs are rated to over 100 pounds).  They do have an external frame, but the beauty is that you can switch out a larger pack for a smaller pack on the same frame, but even the mid-sized packs compress quite well.  Expensive, but an option I'm seriously considering as we plan to do some backpacking next year where we'll have to carry bear canisters for food and potentially carry more water (more water weight).

How large of a pack you need depends on your gear, length of trip (without resupply) and how much water you need to actually carry on-board.  Can you get anyplace that has these packs in stock where you can load up with your gear and have them fitted properly?  I have an Atmos 65 I picked up at a significant discount, but really don't care for the pack too much.  I use it as a loaner pack for those without lightweight gear and who have mostly used crappy backpacks...all of them have loved it.  Again, watch pack capacity verse their weight capacity.  Even with a large capacity (80+liters), some packs limit weight to 50 pounds which really ends up making your pack floppy from a smaller load or extremely uncomfortable with a heavier load.

For me, 65 liters is a large pack.  My base-weight fluctuates between 12-15 pounds and for a summer 8-12-day trip (100-150 miles), my full pack weight (with 2-3 liter of water, 7-8 days of food, and fuel) is rarely more than 30 pounds.  Still, if you haul any significant amount of water, your pack weight will easily creep to 50-60 pounds.  Food choices, and shelter types can also add a lot of extra weight.  Ideally, I would want a ~65 liter pack, some optional add-on pouches for more capacity during colder seasons; large water bottle side pockets (ULA pockets are awesome).  A frame/suspension that would be comfortable with weights up to 60-70 pounds, a decent, expandable storm collar, but still enough compression to minimize a load down to 35 liters without being "floppy".  A tall order, but Seek Outside is about as close as a I can get right now...

ROCK6

I have been told the Atmos is a love hate type deal and to make sure you get fitted kind of why its X off the list I'm 14 hours round trip from any place that has these packs! I have looked at the ULA packs also but its not right for me I need the gear as I move ULA does not really allow that also I don't see where hydration bladder would fit or work and to me that in the 115 deg is the top key! It seems that the ULA is for point to point hiking don't need the items in the pack much until you get to your next point! Also not much without paying more money places to add my compass, GPS or much else any other gear that might be needed! ULA is a great pack if your looking for just a hiking pack point A-B! With the extra gear I'd need to hold needed on hand S&R items why buy a pack that its only real job is to be a pack?

Also does this pack sit off the back so I'm not a sweaty mess?

I bought an Atmos 65 in size L because that’s where my torso size (21”) fell (L fits 20-23”.) It turned out to be too long and the hip belt pad would push my pants down even with the harness adjusted as high as was comfortable, so I exchanged it for an Atmos 50 in size M (18-21” torso) and that fits perfectly.

Any of the AG packs (I have an Aether 70, Atmos 50, and Manta 36) will ventilate well seeing that there’s a mesh trampoline that sits on your back, but you will still sweat. I’m a very heavy sweater and have to rinse my go-to Manta off 2 or 3 times a year when the salt stains on the shoulder straps get too heavy, but I’d buy another one in a heartbeat. I actually may, as my M/L pack does ride a bit lower than I like. It all depends on whether the S/M rides too high.

You should talk to some of your coworkers and see what they use and why it works for them. Anyone who has done that for any considerable amount of time probably has some great advice based on experience.

Good advice here.  This is a very open ended question lol.. "it depends", and I sold packs for 7 years.

Depends on how much stuff you have to carry.
Winter camping you'll always need more room for bulky clothing and sleeping gear.

I'm 6' 3", so unfortunately my sleeping bags and clothing are always larger, so that takes up more room than if I were smaller.

I have 4 different sized backpacks (not including a couple of day packs) depending on the length of the trip, the season, and my planned activities.

I use an old large Alice pack. Heavy but sturdy as hell. Modified with a Molle waist belt and late model shoulder straps. It works good for me.

my current pack is a Seek Outside Revolution with 6300 cu/in bag.  One of the things I like about it is that its light for its size and it compresses down to nothing so there isn't any flopping if its not full.  One of the fears that people seem to have with big bags is the temptation to fill them, having done that in the past it is something I avoid.  I am somewhat anal about what I choose to take or not.

That's good to hear.  I'm really considering an investment in a Seek Outside pack.  I'm quite happy with my ULA Circuit for summer trips as my base weight is pretty light.  However, we are planning a couple of trips where we will need a bear canister, more food weight (few resupply points), and potentially more water and/or a little more insulation (bulk).  I like that Seek Outside frames are quite light yet able to haul insane loads but what's more important is having a competent system that allows you to compress down properly or expand as needed without worrying about the load-weight.

ROCK6

If you want me to take pics or have any questions let me know.  I threw some gear in it.  I am shaking gear out i have a 35 mile hike that I am leading my youth group on this summer that I am going to prehike it to see how it is ahead of time.  Last night I threw my bear canister, EE 20° quilt, thermarest xlite,  borah gear boy and my new to me cuben mld solomid I'll throw my cook kit  and first aid kit in and am going to weigh it later.  With what is in it I used the talon and cinched it down tight holding it by the frame and shaking there was no flopping around.

Yeah, if you have a couple pictures throw them up.  It's interesting to see how much a 6300 cu inch bag compresses.  That's pretty big for my needs, but your equipment sounds similar, so the compression is pretty vital and that's good to hear it doesn't flop around.  I'm looking at the Unaweep 4800 with the mesh talon pocket, but also picking up the top lid and Merlin/Talon daypack.  4800 cu inches is a lot of capacity for me...easily 10-12 days on the trail.   Personally, I just really like the frame/suspension construction along with the capability of hauling a lot of weight.

ROCK6

Here is a pic I just took of the 6300 compressed
Here it is with the solomid and bivy in the talon. Here it is with the bear canister quilt tarp and buy sinched down in the middle of the pack for better weight distribution.

I'm not sure about the OP's work requirements for a bag, but I can tell you I've "lost" important items (GPS, charger, and spare batteries for a headlamp) because they fell to the bottom of a 90L backpack when what I really needed for that trip was about a 60L to 65L pack.

You can slightly underload a pack and compress it, but don't radically underload a pack.

Thanks!  It's amazing how well their packs do compress down.

ROCK6