A fantasy world that's not-so-serious for starters, would be nice. I mean, it must be fantastic and mysterious to spur our creativity yes, but we need not go into so much detail in our first, character-focussed entries. Just let it grow naturally, I'm sure we'll get some decent momentum soon enough!
In a freeform 'creativity driven' environment where basic magic meets near-future sci fi, our characters have all the possible fantasy roleplay options available to them and we can develop them in any direction we see fit... but fantasy influence is low enough that personality still plays an important role.
That's pretty much what I had in mind - the basic magic meets near-future sci fi is perfect. And I agree with everything else, build the world as we go along and just see where it goes from there. That way, as you said, we'll be able to focus on our characters and not get so caught up in other things.
I was also thinking of having a Victorian/Edwardian type of society - especially with the stiffness of the mid-upper class folk. Very set on decorum and how things should be done, etc.
I've also some ideas on my character, been sketching them out on bus & train rides home. :p She'll be a girl from an upper class family, rich enough to be somewhat of a blip, but not too rich. She's the eldest of two, the younger being her brother. Interestingly enough, she's working out to be slightly na´ve, but with a fierce passion for knowledge. That's about it - other little details (looks, full personality, family, etc) I'm still working on. And a name! I'm terrible at names. >_<