Cities within driving distance of Gulf coast beaches?

I want to take an impromptu trip to the beach this weekend. All the cheap and mid priced hotels are booked.. Where would be a city within about 20 miles from the beach that I could stay? I don't mind driving I just need a reasonably priced place.. Lol. I can find a hotel its just hard to find the cities on my cell phone. Thanks! Also, I don't want to go down further than pcb and no higher than about pensacola.