I've been down there twice for spring break. The two big clubs at Panama City Beach that everyone goes to are Club La Vela and Club Spinnaker. (La Vela is known as the Rufe capital of the world . . . seriously.) La Vela is supposedly the biggest club in the US. Both are fun if you are into the club scene. During the day everyone seems to wander the beach between the two clubs with drinks in hand. Some people opt to bury kegs in the sand, etc.
MTV usually has good free concerts on the weekends as well. (as long as you don't mind popular music...the only one I remember with any clarity was Hello/Goodbye.)
Anyways, have fun. Wear protection.
Have fun! :horns2
p.s. -I'm too old for that scene now. I'd rather just sit around a bonfire on the beach with friends and drinks than party it up at the clubs.