Please don't feel guilty. If you do, then I probably should too. We are going in Oct. and I'm leaving my 19mth old home with granny too. My other DD's are 4 and 6, and I thought we could do more with only them there. Next trip, my youngest DD will be able to do more and will really enjoy the trip then. I just wanted to let you know you are not alone.
For all those that said she won't remember it anyway--I took my youngest DD last trip when she was 2 months old. She was fascinated with It's A Small World. Now you're telling me she won't remember it? LOL! I just know she will!;)