As for a new Trek series, I wouldn't mind seeing one set in the past, that's dedicated to exploring Trek's past. We haven't got much of that with Enterprise. I liked the first season, even if some of the episodes were sleepers; the crew for the most part had a great deal of enthusiasm about exploring deep space fo the first time. And I've enjoyed this season as well, Archer and the crew have learned from their experiences, and we see Archer developing into a leader who will eventually take a major role in founding the Federation (which is something that's been constantly hinted at this season).
OTOH, I'd like to see them return to the future. The aftermath of the Dominion War and the events of Nemesis have shaken up the politics of the Alpha Quadrant. I don't really count the stuff on Voyager, since that series was more or less self-contained. The biggest downside to a prequel is that you're setting backstory in stone, and it makes things less flexible for future writers. Another downside, though more subtle is coming up with technology that looks futuristic to us, but primitive by TOS standards. I would say that probably wasn't an easy balance for the production designers to meet.