Nice short paragraph introduction Carcanken. However it would be nice to know more about what you intend this thread for; when you say let's play/community game are you talking about playing a game with a story and community named characters or posting the save and passing off the game every so often, etc?
I only started playing Dwarf Fortress this past weekend but the community has been great in helping me out with it. Since this is your first lets play/community game I figure it could be the first one I participate in too!
However, I do think by letting people choose your embark you're asking for something evil.
I don't want to just send you to a glacier or a desert though. I don't know if I'm going to do this right (please bear with me, it is my first time) but here's my suggestions for embark, in order of importance.
1. As many biomes as possible (at least 3) with above normal savagery. I think it will be a more interesting game to have a wide variety of creatures out and about, and although the savagery doesn't need to be cranked all the way up more would make it exciting.
2. A Volcano and a source of water (aquifer, river, ocean). Especially if there's going to be any kind of mega projects having the access to magma and water will be important. It could also be Fun.
3.Jungle if possible. I've read about people doing both deserts and glaciers, I'd like to get some jungle in there for the giant lions, tigers and...what, no giant bears? Where are the Giant Bears Toady?!
Of course if other people have suggestions go with whatever you like, but if you could combine some ideas that would be cool too.
Thanks for doing one of these, I'm really excited to be involved with my first one. Best of luck with it!
Editing in another suggestion: being cold enough to freeze water would make the varying seasons have more impact, so that would be nice too.