How old are the DD's? Someone else mentioned card games, that's what my parents used to keep me and my brothers from killing each other when we'd get snowed in up in Minnesota. Much later on I realized they also used the card games to help us practice our math.

Risk or Monopoly games can last just about forever depending on how you bend the rules. Other sorts of competitions might help if the girls are close in skill levels. Challange them to build the tallest free-standing Lego tower (or a tower made of canned food if you don't mind dents). Get some rope and award chocolate to the first person to memorize five knots (your DW might go for that if she's anything like mine).

Get some candy recipes and have yourself a good old-fashioned taffee pull or make popcorn balls or fudge.

Blow off excess energy with a pillow fight or a marshmallow war.

Good luck.
-Blast