Fun things to do in or near Indy?

My wife and I both have a birthday coming up in the next two weeks. We have a 10 month old daughter...ever since she has blessed our lives, we haven't been able to go out and enjoy each other's company as much as we used to, and I think that's starting to get to my wife. We live near Indianapolis, and I would like to do something nice for our birthdays, or possibly go somewhere for an overnight trip. We would bring our daughter with us. Any suggestions?