I found a Kayak as a great way to get to new spots that you can't access easily by wading. Sometimes just getting accross a channel to the other side can make a big difference. I found it is tough to fish out of one for more than 4-5 hours at a time without getting out and walking around.
I think you'll find a SOT style as a bit safer for fishing, but many fish with no problems in a sit-in style. There are lots of nice kayaks to choose from, best to try some out before buying one.