I think Panama City Beach is the trashiest place on Earth, and I wouldn't be caught dead there between the first week in March through the last week in April. But, I don't dig the same things a lot of people do--cheap booze, lots of parties, and the ability to hook up with a lot of different people. If that's your bag, go for it. But, if you're looking for a inexpensive place that isn't total Redneck Riviera, you can always visit the towns to the west of PCB. Lots of college students go there, it's clean, and there's still a lot to do outside of the beach.
If you've got the money, I'd suggest just leaving the country altogether. At one point in the spring, it was cheaper to go to London (from Boston) than it was for me to fly home to Florida. The drinking ages are lower over there than they are here, so you can always bring your newest members and littles.
It's not all trendy Euro over there, either--if you want an old fashioned American pub, you can have that, if you want to drink a real Black and Tan in Dublin, you can do that--and pretty cheaply. Clubs close WAY later than they do here...I stayed out from 7 PM to 7 AM one night, and was able to take the bus back to the place I stayed.
From the looks of it, the Mr. and I are heading to Dublin, then taking a hop to London for Spring Break. I'd imagine I'll spend about the same amount in 5 days in Dublin than I would 5 in Cancun.