Here's a chart the Davidson people made up that might be helpful:

http://www.davidsongifted.org/db/Articles_id_10642.aspx

We've been doing EPGY; DD started with I think the 6th grade math, which she did pretty quickly, but really slowed down with algebra. She was working her way through algebra this past year but still isn't finished--she wants to learn math (in theory) and picks things up quickly but then is resistant to actually sitting down and doing the work. I got her an AoPS book (Intro to Counting and Probability) to work on independently in school this year and she told me she was really excited because she had started it and "they found a way to make counting interesting to me--impressive, huh?" The AoPS stuff seems to emphasize understanding in a different way and their site says it was designed by people who were good at math as kids and would have liked to have books like this. So I'm hoping DD will be more enthused about it, but we just started. I have to say EPGY seemed a little dry but I am not mathy myself and don't know how you could really make algebra fun; it seems almost like math facts to me. Maybe we'll have to look at the AoPS algebra book and see if it can do better. Somebody posted here on another thread that even if you've seen a subject, the AoPS treatment may still be useful and interesting, so I am optimistic.

Anyway, good luck!