I was really debating this, too. . .
We'll be doing the Princess Tea Party with Aurora (and going to the BBB) beforehand. Additionally, we'll be having breakfast with Cinderella and will be going to Chef Mickey.
In the end, I think I've decided I'm ONLY going to bring the Aurora dress. My DD will also wear her princess dresses all day long every day -- but not just the dresses, she MUST also wear a crown, shoes, and her "jewels" (clip on earrings, necklaces, rings. . .). So, for our own sakes, she'll wear normal clothes at Disney, but on the day of the tea, she'll receive a "gift" from Aurora, beautifully wrapped, etc. It will be a new Aurora "gown", shoes, maybe even a pretty necklace or something . . . I think it will make THAT day all the more special, too.
We're not going until May, though, so maybe I'll change my mind again before then?!!?