We have only done offsite 3 times.
Twice at the Holiday Inn sunspree. It was very good and reasonably priced. They have themed rooms where the kids and adults can have their own space and kitchenettes which are so convenient. It also depends how old your kids are. No real restaurant however but this is a great place for little ones.
We stayed at a Disney hotel outside of Downtown Disney/the Best Western. It was awful!! Bathroom toilet did not work, shower water went from really hot to icy cold in 15 seconds and no towels or proper lighting at the pool. So ask around and do your homework. I would think outside the park there are alot of options to "lure" you away from onsite and the deals should be great too.