I've done the same... i have a TileMap engine built and am working on the simplest battle engine known to man, except I'm having problems with it >.<
How would you consider doing your battle engine? Right now I have all the map data in static arrays in a MapName.cs (like Town.cs, Dungeon.cs, etc)... I have a few ideas but i've been looking at code all day fixing up the tile engine and commenting the hell out of it before i posted it on the net.. was just curious how you would go about doing it.
BTW, if you wanted to see what i've done, the link is here:
shackrpg - Google Code
Keep in mind its my first "big" project, never programmed before in my life and learned less than a few months ago. If you have any tips or suggestions, i'd love to hear'em!