Looks good so far.

The geometric patterns in the ground remind me of the old Sonic games. You should add some more variation though - maybe take an idea from those games and use a similar style of eyecandy. Eg make parts that stick out or are indented: see this screenshot http://www.soniczone0.com/games/soni...hz-act2map.png

It would be quite easy to add tiles for that, it looks good, and it fits well with the sort of design you have going.

Oh, and in your first screenshot, those buildings in the background are far too bright. They look too similar to the floor, which means players might think they are masked. I would suggest darkening them or desaturating them, or both. You want your background to look good, but you also don't want it to stand out a bit less than the foreground, even if it's just a tiny bit. Right now they both use the same colour.