I encourage every parent here with small children to enroll in Florida prepaid or your state's equivalent. My wife and I put three kids through and couldn't have done it without it.
I don't know how old your kids are, but about 8-9 years ago, after my oldest son was already enrolled, the State Legislature showed contracting with the state is an uncertain endeavor. Unless you were in for a certain number of years (we were not even though we had a decent amount already paid), they changed the plan on participants and added a "tuition differential fee" that is not part of the prepaid. Plus, as you might expect, those fees are really only charged at schools kids really want to go to, with UF charging the most. So, your "tuition" is covered, but the "tuition differential fee" still isn't, i.e. perhaps as much as 60% by the time my kids get there would not be prepaid. As a result, the 529 plan might be a better, and more flexible, option.