Lerxst
spaghetti and blankets
The Mrs. and I have been thinking of picking up a couple kayaks. Looks like it'd be fun, and we've got a couple of nice rivers (Monocacy and Potomac) within minutes of our house. I have no idea what type to get though. So many choices...open or closed....long or short....wide or narrow. I see a closed cockpit (I guess it's called a cockpit) in @Lerxst's pics. Think I'd prefer that over the open. Other than that, not sure what to look for.
Don't know about your area, but a number of lakes around here do not permit sit on top kayaks, only sit inside. Check around to see what restrictions are in place where you'd use it. Thinking about where you want to paddle will probably help narrow down your selection. Might be some local rental places where you try a few different boats out. Look at the types of kayaks people are using where you plan to paddle.
http://www.paddleshack.com/tips/tipsonselect.html
Craiglist is a good source around here for used boats and accessories. http://www.austinkayak.com/ is a good online shop.
For couples paddling, a canoe is a great choice too.