I like to be DM. I prefer it. It really lets me stretch my imagination legs and create something that I can share with my kids.
Lately though, my kids are stretching their imagination legs in relation to the game in terms of wanting to create sub classes and such.
This combined with my own inventions and creations really makes me wish I could be a player. to take full advantage of some of these cool things.
I don't run a PC while I am DMing, I think it's unfair to the other players. I have been known to send an NPC along to fill out a party, but I make the character a kind of a 2 dimensional participant there to acquiesce to the group leaders (unless it's outside of alignment, etc..) which is nowhere near the same thing.
The kids, on the other hand, are just having a ball, even when their PC's get killed or really spanked bad by another party or monster. Of course, when they can make something really cool come about with their PC's, they really get raucous and loud.
Who knows, maybe someday I'll get a chance to join a group of 1E folks and just be a player.