Ah, I gotcha.
Hm, well, whatever is hard to do when you've got little ones around. There are some projects/chores around the house that can be very tough to get accomplished without a good block of time, so those things can be nice to get done. I like going out to a bookstore and browsing with a nice cup of coffee. Napping is nice, as is giving yourself an at-home spa treatment (doing nails, etc.). Renting some movies that aren't suitable for kids is another nice way to while away an evening. I'm a big reader, so curling up with a good book is pleasant, too.
I'm sure there will be some other ideas.