Hi, Debbie! I'm going to give you a couple of ideas since I am not sure how old your daughter is, etc... If your daughter is young and has a favorite character (a princess or one of Mickey's gang, for example), have a present from that character waiting for her with a "can't wait to see you letter" from that character inside and a small gift representative of that character. It doesn't take too much time or imagination to craft a short letter and add some clip art to it.
If she is older, you may just want to give her a set of Mickey ears that you can buy on the Disney Store website under the Disney Parks Merchandise section.
If you are really crazy, like I've been known to be, write a song about your upcoming trip to a familiar tune, video tape yourself singing it, put the DVD in a gift, and watch the fun when she plays it. (I've also sung LIVE versions of "vacation" songs. That's fun, too!) Happy planning and have a Magical vacation!