Combining space and infantry has got to be the way forward, a map combining both is what will make this mod stand out. I'd love to be able to fly into a Star Destroyer/space station/Rebel cruiser, then hop out and start fragging away. But the objective needs to be a good one to keep it interesting once that first novelty wears off. Oh and with asteroids, lots of asteroids! :-)
Agree with most other people's requests for big land vehicle based maps, maps where you can really let rip on a speeder. But I'd be surprised if that wasn't already on the way considering the amount of vehicles that have been built for the mod. Can't wait.
Endor is definitely the way to go for infantry maps, a good diverse landscape where you can roam quite freely and come at the enemy from lots of angles, not the claustrophobic maze that is Mos Espa.
I think it's important to approach designing a map without thinking about it being Star Wars. Forget Star Wars. Think of what would make a great, original, and fun map, and then stick it in the SW universe somewhere, but without being too constrained by the canon. Go beyond the obligatory Endor, Hoth, Tatooine, Death Star maps.
Did someone say sea maps? With Mon Calamari soldiers? Oh, that would be cool ;-)