Echoing others about companionship.
Some escorts even title the longer appointments "dinner and dessert", "night on the town", etc reflecting the kind of things they tend to do in those time periods. Between 3 and 6 hours - usually some sort of meal or sometimes, movie or event, followed up by sex. Once you get into travel, 24-hour+ arrangements there is anything you both are interested in exploring.
However, I also often had 2-hour sessions where conversation only lasted 10-15 minutes during the recharging period and we never even made it to massage: it was all about slow, passionate exploration where we both were completely lost in each other. And like Missy Mariposa, I find longer sessions more intense and powerful since you can fully build anticipation - and you both are on the same wave where you believe that seduction starts with the mind.
Also, I know for a fact that a lot of men seek this: I have a 2-hour minimum and yet I never had any trouble finding clients. They just don't get discussed on the boards as often. Most of my regulars are either off-boards or lurkers.
It's interesting though that somebody has to come in and tell the world they don't care for longer sessions... It's pretty obvious that a lot of people have no interest in them. But some do. This thread was about discussing the latter - reasons, views, preferences - wasn't it?