I like new areas of a game. I don't know where things are. To me, that's a feature. One of my great loves of sandbox style games is just wandering about and finding things. It's a pleasure. On the second play through, that same enjoyment just isn't there. Play gets somewhat more mechanical, rather than experiential. I need that great unknown to keep my attention all the way through a game.
I sent in a pitch to Dragon magazine's open pitch season. I got a refusal, and an explanation. Yes, that's a high level refusal. Coolness.
I have trouble writing for 4th edition. I just can't get my brain around hacking it. I can't do setting-specific writing, because I don't know the settings. The rules part is just too well tuned for me to play with much. I think the game is well rounded enough that I'm just not left wanting anything, and that makes it hard to pitch something, because I struggle with finding something to pitch.
Much of my 3rd edition homebrew was entirely based in "what hasn't been done that I see a screaming opportunity to have fun with." I then run with the idea.