A gaming groups are a strange and varied breed. Mine certainly is. One of the most challenging things about GMing is understanding the players motivation. Having a master degree in psychology helps that, but when in my case I'm not sure how anyone could do it without one.
Let me explain. The motivation of everyone at the table is presumably to have fun. But what is fun and how do you have it. A (remarkably scientific) exploration of what makes a game fun was conducted by XEODesign examining games in general, but video games more than anything else.
They idenified 4 kinds of fun...and graphed it with this little tidbit of insanity.
Without going to far into it, you can easily figure out that RPGs fulfill all of these in many situations. Hence the longevity of the hobby.
But each of my players gravitates toward one over the others. (I'll use character names from the most recent game).
Cassidy: People Fun. Cassidy comes because she likes to hang out with people. The other forms of fun are inconsequential. The game itself has little or no real impact, although "Easy Fun" is secondary. Movement toward Hard or Serious fun has a risk of lowering her interest.
Joel: Easy Fun/People Fun. Joel is hard to figure sometimes. Of the two he seems to gravitate toward Easy Fun over People fun, but the line is thin. He appreciates Hard fun, but Serious Fun tends to put him off somewhat.
Ali: Easy Fun. Like Joel, People fun is almost as important, but the line is dark enough to allow a more certain assignment (barely). Hard Fun is less interesting to her, but not off putting. Of all my players she is the only one I can imagine enjoying Serious Fun, and very well may. Including that, however, is next to impossible without seriously impacting other players.
Lucian: Hard Fun. It's not even a question here. Like most of my players, Serious Fun would turn him off like a lamp. He gets into Easy Fun, and like the People fun, but often enjoys activities that have little or none of either.
Bea: People Fun (?). Bea seems to enjoy the social nature of the game, a close secondary is likely Hard Fun with Easy Fun being third. They are fairly closely clustered and likely varies depending on her day-to-day social interaction needs. Serious Fun is, at best, dis-interesting and at worst, off putting.
Myself: Hard Fun. Given my own limited ability to self-explore honestly, that is my best guess. Most of the games I gravitate toward seem to capture the elements of 'hard fun' over other kinds. Like most of my players, Serious Fun is 'meh'. I can imagine myself enjoying it, but not on a regular or general basis.
So how the hell do you GM for a group like this? It's a challenge to be sure. Let's suppose I dropped my "Easy" fun players. I'd likely get bored with the game because it would be mostly story-driven with only a limited amount of gamism involved. If I dropped my "Hard" players, I'd get sick of the story-less gaming.
Most of my players enjoy the People fun on some level. This tends to be the dominant factor in our games. In many cases we don't even get to the game, we just hang out. We could just as easily play Wii and have as much fun. The "hard" and "easy" motivations would eventually cry out for something besides chatting, but once satisfied that would subside.
The truth is, I have an easy group to GM for. The "people" fun happens naturally and as long as some of the other funs are there, everything will be fun. The balancing act between "hard" and "easy" is really secondary since most everyone is just happy to hang out.