Thanks for the ideas and great sites! I'll be doing some picking and choosing (and printing!) this week.
I may ask DH to clean out the garage (he keeps it pretty clean anyway) so there's room for some ball-bouncing, toy-truck playing, jumproping, etc. no matter what the weather. I have a big roll of newsprint I can tape down and let them color away. We'll have 5 kids under 8 here, mostly boys, and they're wonderfully rambunctios.