2 hours to hell sounds about right. That was my limit on a stock GS500 seat. Seat comfort is a pretty personal thing--what works for one won't work for others. There are some basic biological factors at work though:
--Circulation: without adequate bloodflow, nerves become irritated and tissues become starved for nutirents, resulting in aches. If the seat foam is too soft/hard/thick/thin (it depends on temperature, the rider's weight, age and fitness) then the tissue under your "sit bones" is the first casualty. Narrow and slanted seats compress the edges of your thighs in a similar way. Pant/underwear seams add additional hotspots to compress tissue.
--Ventilation: it's ugly, but we're primates and primates sweat to regulate body temperature. Most motorcycle seats are vinyl and most gear is leather/nylon. This means your (salty) sweat has nowhere to go, collecting on your skin. Damp cloth chafes, tugging at your skin and bacteria love it, resulting (eventually) in the dreaded "monkey butt", which is basically diaper rash. It's no joke, despite the name.
Manufacturers of custom seats, seat covers, wicking underwear/shorts and various topical creams do good business catering to the discomforts of the modern motorcyclist. Start with the cheapest options first and try to narrow down WHY you feel uncomfortable. None of the options look stylish, but remember your seat was designed to fit the bike, not you.
A beaded seat cover is probably the best place to start. It's simple, inexpensive, you can leave it on the bike, spreads your weight out and ventilates too. It looks a bit goofy, but nobody can see it while you're riding (least of all you) and it's easy to take off if you're trying to impress a date with your ride. It's more slippery than the stock seat cover and some dislike that.
There's volumes of testimonials out there. Start digging and good luck.