Okay everyone - thanks for the advice.
In case your curious, I think I'll stick with Aikido as my only martial art for at least a few more years. I'm coming up on 9 months now and before I'd be starting anything, I'd probably be around a year anyway. I'll wait about 4 more.
I do think I will do yoga though. I think the cross training benefits win out, plus from what I've heard/read, you can still get enough out of it with only 1 or 2 classes per week. That seems to work with my schedule okay. Now, I need to find a class that isn't all women.......or maybe that's one of the benefits.
Either way, that's a post for a different website at another time.
Thanks for the advice.