Cindy have you ever heard of this site:
www.hapari.com
I have several tankinis from there and they are fabulous! They are true to size, too. If you end up getting one, here's a coupon code for 10% off: JEN2011
If you have questions on sizing, please PM me, I love them, they're flattering, and everything stays tucked in while you're playing with the kids. I can't be bothered by things flying everywhere, if you know what I mean.
Have a blast in Disney! I love that place, it's been 4 yrs since we've gone and I'm dying to sneak a trip in this year... fingers crossed!