I've fished from float tubes over the last 40 years. They have evolved from inner tubes with canvas webbed seats to the inflatable mini-yachts we see on the market nowadays. If you want to go for versatility, stability and load capacity, check into the "Watermaster". http://www.bigskyinflatables.com/ I've used one for about 15 years now and I think they have more going for them than the other designs. They ain't cheap, though, starting at about $1500.
Pat