The problem would be that with DC you'd have multiple locations, but it could easily be rectified with a teleportation system. You could catch a lift from a mystic with teleportation powers, use a JLA teleporter hidden somewhere and go places like the Watchtower satellite. As far as characters, especially if you try and give a few villain characters spots, you could dig deep in the well and get just as many characters from DC. You could have half a dozen Earth Green Lanterns with different suits, constructs, etc. Toss in the Metal Men, Doom Patrol [Negative Man FTW!], the extended rosters of the Justice League and Teen Titans and you'd have a pretty good cast. I could imagine a Metamorpho Lego style looking like the Sandman from Lego Marvel. The various Starmen would be sweet. 

~KL~