I have 2 espris. One has the Sevylor high back seat (around $125) with pockets and the other the bog standard Viking seat (around $100). Both are very comfortable but I find that the high back seat can interfere with the back of my PFD. My workaround is to jiggle the PFD around until I get comfortable. The storage pockets are very useful.
Like sunshiner i use the stander Viking high back seat that comes with the two water bottle holder and a massive big pocket. The water holder and big pocket clip off so it can be use as a belt.
But i find my ass goes dead after about 3 hours on the water so im going to put some padding in.