I'm taking a brand new lens this trip, a Canon EF-S 15-85 f3.5-5.6 on my 7D
I've been using a 28-135mm but found I'm always needing more wide than zoom at WDW. The new lens is much sharper also.
I'm going to carry my 70-200mm F4 L for my second lens but figure it will be in the bag most of the time.