Do you have enough members so that you could just divide them up and have each group attend a different event? That's sort of what we did...of course, most people wanted to go anyway just because it was fun so we always had a pretty good turnout (especially to paint the windows), but for the things that were a little less exciting, we just designated a group of members to go. Maybe your sisters aren't really excited because this is the first year you're participating and they don't realize that it's more fun than work.
Oh, and the meetings...everyone always gripes about meetings, no matter what. That's just how it goes.
We could miss 2 meetings a semester, but after that we got fined...that did a pretty good job of keeping meeting attendance up.