Depends on your definition of "nice". For location, Skidaway Island SP is great. It is an easy drive into Savannah. The park includes hiking, biking in a natural setting. no sewer at site, but bath houses are available. Hardeeville RV park is a basic, no frills, full hookup (no bath house) cg - again, very easy ride into the city. It is a Passport America cg, if you are a member.
'02 KOUNTRY STAR DP
2012 HONDA FIT "PUMPKINMOBILE"
GILLIGAN- 1ST MATE CAT - 3 HR TOUR
Hilton Head Island RV resort and Marina is the place
Very very nice. It is actually an RV condominium. Each site is individually owned and landscaped. Prices to buy are $60K to $250K. Rentals are about $50/night. Has 2 pools, hot tubs, tennis courts, restaurant on site, marina w/charters and rentals on site.
EDIT It's about 40 miles to Savannah but I consider anything within an hours drive as close by.
I agree with Water-Bug. Unless you must be in Savannah, the 2 campgrounds in Hilton Head are resorts. There is one on the intercostal waterway and has a few sites on the water. And the one Water-Bug mentioned is farther inland. Both are very nice.