I've had 2 experiences where I fucked a guy for multiple hours. First time was a guy I picked up on AOL (so it has been a few years). He came over after work (and he went home and showered). We had a few drinks, we messed around and then I started fucking him. I fucked him for an hour or so, we would slow down, lay there and talk while my dick was still inside him, watch some porn and then I would start fucking him again for another hour. We repeated that for most of the night, he finally left about 5am. Never saw him again after that, but he did have a beautiful ass.
The next time was a similar experience. A guy that I picked up at the adult bookstore. We went back to my place, I fucked him for about 4 hours. The fucking wasn't constant for the 4 hours, but it was off and on. Finally we both came and collapsed on the bed. He woke up a few hours later and left.
I remember one time I bottomed for 3 to 3 1/2 hours. This guy and I had been flirting with each online for almost 5 years. He would get a new boyfriend and he would disappear for a while. He would be online, we would flirt, he would start dating again and then disappear. We never hooked up because he always said I lived too far away (I'm probably 20 minutes away). One night, I was hosting in a dark hotel room. The hotel was very close to where he lived. We started talking and I reminded him that he has always teased me about wanting to fuck me. He said he really wanted to fuck my ass, so he agreed to come over. He is a bit of a germaphobe, so he needed to take a shower before he came over and he wanted me to take another shower, even though I had one just an hour before we started talking. So I took another shower, and got ready for him. He came over and we made out for a while (seems like a germaphobe wouldn't want to french kiss, but what do I know). We got naked, I sucked his dick, he sucked my dick and then he wanted to see my ass. I flipped over, he started to rim me (again, not a very good germaphobe!) And then he started to fuck me. We fucked for probably 2 hours when he needed a break, he wanted to know if I wanted to share some coke with him. I politely told him no. He did a few quick snorts and got right back to fucking my ass. He went for another 90 minutes or so. He got really into it and was pounding my ass hard. It felt incredible. I finally hit the point that I couldn't take it much more. So I started squeezing down on his dick. This made him cum which made me cum. It was incredible.
I think the only reason I could take him for as long as I did was because I was really into him. He is very hot, has a beautiful dick and we had been flirting with each other for so many years. He was really good at topping and I really enjoyed it.