I decided to use the same design I am for OpenXna RPG (xml tileset file and text map file.) There a few differences (in my side-scroller any tiles can be any type, whereas in my RPG format each tile has a specific type.)
Animated tiles work great. I've setup continuous, reverting, and no-loop loop types. I also setup loop delay, so that you can specify a length between each loop (1 2 3 wait wait wait 1 2 3 for continuous and 1 2 3 wait wait 2 1 wait wait wait 2 3 for reverting.)
The new map system also uses the camera idea I mentioned a post or two back. The rendering function takes a reference to a camera that the game takes care of. The map system also keeps the camera in bounds.
I also set it up so that a map can be bigger or smaller than 125x125, which will be nice when I want a long, midly-straight level. It'll also be nice for one of the levels I have in mind (elevator type level.)
Anyway, new screenshot:
You can't tell, but the Mario-brick is animated with a frame-delay of .25 seconds and a loop delay of 2 seconds.
Not much left to do, so I'm off to finish.