I've seen some of the flatter games (Zone Zeal, Triple Play) in action, either live or by videotape. I've also seen games with monstrous climbable field features (Stack Attack, FIRST Frenzy: Raising The Bar) the same way.
Put simply, I love games with the big field features. If for nothing else, it makes the field look more interesting. Compare:
FIRST Frenzy
Triple Play
Also, a good use of colors can contribute to a field that draws folks in more. (For reference, both of those pictures were taken in the same venue, the Colonial Center here at USC.) In FIRST Frenzy, we've got colors all over the place--purple balls and yellow 2X balls, of course, but then we have this ginormous red and blue platform usually stuffed with the aforementioned purple and yellow balls, plus a few robots on the bar. Triple Play has the tetras and the goals, with the vision targets at the bottom of the field. (Of course, with the CMUcam in the kit this year, I can see how there's a method to the madness with a simple field.)
That being said, I would be ecstatic to see an interesting center feature again, one that would draw robots that way, instead of away from each other. (Ten-point bonus for all three robots touching the center goal, anyone?)
If/when Dave posts the "you-design-the-2006-game" thread, I'll develop this the whole way.