Great advice above... I like a cooler with wheels since I tend to bring a lot of stuff with me and it's too heavy to carry and I can get everything on the boat from the car in one shot. I also mounted some PVC pole holders on mine since I usually bring 2 poles and it makes it convenient to transport and I have the 2nd pole handy when I need it... Lastly, I like to fish the stern where there's usually no seating so having a cooler strong enough to sit on is a big plus.
As far as size 50 - 70 quart is probably a good happy medium. Anything bigger it will become too clumsy and or take up too much room.
If you fish with us on any of the trips we run here you might also want to have some way to lock it... Lets just say some of the guys have a preference for other people's beer and some strange things have wound up in others coolers
