Read that title a little to fast?
CoC compliant thread alert.

Just closed on my first home for my wife an on the 15th of July and have not stopped moving since. So many things to do. So much money to be spent.
Got my bank account hollering "UNCLE!!"  But I have also started to prioritize all the projects I need to accomplish for this home in the first 30, 60, or 120 days, and one of the first things that needs to be done is to get my deck sanded and sealed.
This house is only 5 years old, and thus so is the deck. The precious owner appears to have maintained everything very well while somehow completely neglecting the deck altogether. It doesn't appear to have ever had a stain coat or sealer ever applied to it, and it's some shoddy craftsmanship to say the least. The owner didn't build the deck though, so I am not blaming him for that part.
I need to ask the guys on here a few questions,
1. How do I know if the wood on the deck needs to be replaced it it can be sanded and sealed? Almost all the boards are cracked and have some splits, which is to be expected after 5 years of negligence.
2. Would it be possible to gauge each board individually and replace the ones that are in the worst shape or would it be more prudent to do a complete rebuild if I'm going to replace any at all?  
3. What sort of wear should indicate to me that the wood SHOULD be replaced? There doesn't appear to be any rot or termite damage, the wood is just basically OLD and worn out, but not weakened in any way, at least to my best judgment.

I am not like Mr. DIY, but I would LOVE to be able to not rebuild this deck.

Pressure wash, sand then stain.

I wouldn't worry about structural integrity after only 5 years. The original stain probably lasted 3 years. 2 years of neglect is bad, and shortens the life for sure. But it is probably far from rotten.

Decks are a lot of work.

I find that a pressure wash will make the wood look almost new. There are going to be cracks anyway.  If they are bad enough you can pull the board and flip it over and it will be new again.

My house had the deck with a green slime all over it. I power washed it.  The stairs had 3 steps and they were bad with the edges rounded off. Removed then flipped them over and screwed them down again. Looks new.

There is so a wood bleach that will return it close to.the original color.

I posted a thread here about what deck coating is the best. I've used Flood CWF on a past deck and it did well. I'd use it again but was curious if there is something better.

Can you post pics?

As others said, pressure wash and stain with a good quality stain.  Don't sink a lot of money or time into it if it is as rickety or shoddy as you say, but do protect the wood.  It will be fine for at least three years then probably time to restain.  Be careful pressure washing, you can etch old dried wood very easily. if the nozzle gets too close.

Agreed, I just pressure washed my last weekend.

Be careful getting too close as you can damage the wood.

I've done some minor sanding of rough spots and have let the wood dry out for a few days this week. I'll be staining it this weekend. I can tell you the thing looks almost brand new after just the pressure wash.

As for the boards if you feel comfortable walking on them and see no visible damage such as large cracks or bowing when you put weight on it you should be okay leaving it alone.

If the deck isn't rotting and is solid i would pressure wash and apply a coat of textured deck paint.  I did that at my old house, worked great.  make sure the deck is dry before applying.  The paint rolls on thick and will eliminate any splinters, cracking etc.

as an earlier post said, don't pressure wash to hard or often because it will destroy the wood.  Been there, done that.

I appreciate all the responses.
Got the washer, sanding stuff, and Thompson's all ready.
Went with seal instead of stain for a couple reasons.
The color of my house is a grayish blue, and if the wood comes out of the wash looking as new as has been indicated, a transparent seal will be just fine as compared to a shade of stain. We get plenty of rain and snow where I am at so the water protection seemed to be more important to me than the color of the deck itself.
I will try to post before and after pics. Gonna be a blazer tomorrow. Can't wait.

Thompson's isn't very  good.

This is a good option as well. It seems paint tends to last a little better too.

Thompsons doesn't do well in the sun in my experience.

It is hardly worth the work of applying it.

I have no issues with the grey the deck turns. The wood under it is still good.

In my experience, it works well in the shade. The areas of my house where decks get little sun, it has lasted a while, and provided good water protection from snow/rain.

The places where the sun hits for 8 hours or more a day, it is gone after a year. It also doesn't hold up to a lot of foot traffic.

20 year old deck.  i don't want to replace it as the adjoining kitchen is going to get larger in a couple of years.
i powerwashed it "gently", then used Sikkens deck stain.

http://www.perfectwoodstains.com/view-product/cetol-srd

ar-jedi