As a fun 'summer homework assignment', have the 2 older girls to each write a list of 10 (or more) things that they would consider a 'fun activity' that you don't normally do. (Tell them it's 'for future reference' for you). Read their lists and if they both have something on there that's similar and that you could feasibly do, go for it! (Also try to manage making some of the other stuff happen periodically 'just for fun'!)
Oh, and if you do the fondue and don't already have a pot, call all the local 'thrift stores' in the yellow pages and see if they have one. I've seen them at these type places (Salvation Army, Goodwill, the city mission, etc)