Makio: Thanks for the advice. And yeah, I definatley plan on changing the ground and grass. I know it doesn't mesh, it was just because I haven't made those tiles yet. And I needed the buildings to stand on top of something. Most of my game takes place in the city so I figured I'd worry about the buildings first. So yeah, don't worry about that. Although, grass is the bane of my existence and I can never make it without it looking like jungle grass. =\ I'll just have to keep trying.
About only three sides showing, I looked at the RTP and Green Raven's breeze tileset for reference, and for both of them, the back side wasn't showing. And then I tried to add a fourth side to see what it would look like, and it looked absolutely terrible, so I'm sticking to the three sides.
And yeah, I think I need to move the top building back a little. I think I'll make a seperate tile for the case that I want to tile buildings.
Thanks for all the advice. =)