During my teenage years I spent days on end in both sea, and white water kayaks. Multiple week long river and lake paddles, some decent whitewater more then a dozen times. I was also a sailing and canoeing instructor at a summer camp, never got my kayak instructor status but I spent just as much time in them.
I sold my white water dagger freefall about 5 years ago because I pretty much stopped using it, hind sight 20-20 I probably should have kept it.
We still have 3 old town flat water boats, a guide boat, and a large canoe at our family's cabin on a small pond so I always had access, just had to travel to get them.
Any ways where am I going with all this? I am going to point you in the cheapest direction possible, because my wife and I just did exactly what your looking to do.
Anyways with a couple rivers and really nice lake very close to our house we decided we wanted something to get us out in the water, after some discussion we decided two "cheaper" kayaks would probably work best for what we wanted to do. I figured we were looking at spending something in the $500 range... I looked for used locally but found nothing but crap.
I started surfing local box stores and came up with a pretty affordable option at wally world:
http://www.walmart.com/ip/Lifetime-8-Daylite-Kayak-Orange-with-Bonus-Paddle/49312810?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227037677046&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=92169712457&wl4=pla-183819894737&wl5=9005206&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=49312810&wl13=&veh=sem
Two lifetime daylite kayaks. They are 8 foot sit on tops with a max weight of 250# and I would say that holds pretty accurate. Works fine for me but I bet another 100# or so and it would sit pretty low
us:
Me 5'8 200#
wife 5'7 120#
The weight does make a bit of difference in a smaller boat like these, as my wife can go faster... I am a very strong paddler but wife can still pull away from me flat out, which of course she thinks is great. I would say they paddle like a cross between a white water boat and flat water boat. Not bad for an 8' boat. You won't be doing any long distance paddling with these, or any class 3 rapids, but they could do everything inbetween without breaking the bank. As long as your not out to impress other paddlers these boats or similar will do you just fine.
We have actually had a blast with these. I would recommend any budget boat to someone looking to get out every so often and just enjoy the water. We have no intentions of paddling multiple or long lakes, or crazy white water, we just want to get out there on a nice day, with a cooler of beer and enjoy life. No hurry, and no expectations just being on the water is fun. Truth of the matter is most people get a boat or two, use the heck out of it for a few weeks/ months then they sit, used maybe once a month if that, well if your only dropping 300~400 on a couple kayaks then its no super huge loss. Use 'em when you can and enjoy.
Don't go high or even medium end unless you truly need to. Its not worth it. Plastic technology have come a long way in the past couple decades and I have no doubt these entry level boats will hold up just as good as and old town, dagger, perception with average recreation use.
Two fit perfectly in my small utility trailer with a couple straps...
We paddled around, drank some beer, covered about 3 1/2 miles our first trip out, spent over 4 hours on the water, and had one heck of a time for very little money. Our days off don't sync so its hard for us to land an afternoon together, but we plan to go paddle every chance we get. These entry level sit on tops surpassed my expectations.
Even rocking my old whitewater rescue pfd. No posing, I actually use to paddle a lot of white water, and there is no point in getting another pfd when I have a nice one. It does feel a little tighter then It used to though!
In summary, don't think you need to spend big, nothing wrong with whatever entry level boats you can source in your area.
I ended up getting these on sale for $139 each at my local wally world...
ETA/ any specific questions on these boats or paddling in general I will try to help. Haven't done much in the past decade but prior I spend much time on the water.