the pretty "N" game has nice diagonals and round tiles collision,
and they wrote excellent tutorials describing how they did that efficiently (flash was too slow when the game came out)

tutorial B

Well, thanks for the help everyone. i certainly have some more insight to this issue, but i do think i'm going to stick with polygon/line-based collision detection for the map. maybe someday, when processor speeds are measured in terahertz (that day is soon), i will use bezier curve collision detection. but for now, i will just stick with line-based collision detection...kinda like line rider.

now i have to figure out how to do line-aabb collision detections...but that's for another thread.

thanks for the help everybody!