Possibly the best hotel in Crawley/Gatwick is the Arora, but Crawley is a dump. There are several small country hotels hidden in the leafy lanes of the area and as long as you have a car, that would be my choice and is what I usually do when in the area.
Otherwise, as others have said, Brighton. It has loads of interesting restaurants and a lot of variety, ranging from spectacularly bad tourist traps to very good. Quite pleasant to walk around, a couple of cinemas, lots of hookers if that floats your boat, a big gay population (ditto!), all in all it's probably the best choice.