I'm surprised no one has mentioned this before, but when I reach my goal (probably another year from now, down a total of 112 pounds) I would like to go on a trip. My husband and I have done 2 cruises so far, and I would love to go on another Caribbean cruise when I would look really good in formal clothes, bathing suits, etc. The challenge is that cruises are geared toward unlimited food... but something like this would be a huge reward for me.
Aside from that, and the new clothes that I'd need, the biggest reward for me would be the pride I would have in having reached my goal. And like Kaitie, I think my husband and I are ready to have kids, and I want to be at a healthy weight (and have been there for at least 6 months) before getting pregnant -- better for both me and the baby. Conception on a cruise ship isn't out of the question.... <grin>