There's enough for me, but I'm happy watching grass grow at my age.
I wander the resort and bird watch and Dolphin watch . I visit the Wildlife Refuges - Pinckney and Savannah.
Eating out and planning special meals that I enjoy are big for me.
Also sometimes I'll browse the second hand stores looking for that long lost masterpiece. Never find anything.
Walking the beach early morning wrapped up well is a habit of mine, and waiting for sunrise. I'm usually the only one parked under the beach house for this, but by the time it starts to brighten a bit others come from the homes and resorts nearby. I'm a super early bird so I don't expect many to enjoy stuff I do on vacation.
Decorated boats are fun for a walk around the marina. A few stay decorated all year.
Stuff that holds little interest: Pluto. After one or two times, over. If Grandchildren are along, that's a must. Pluto was the resort's replacement for Shadow and B'Lou. Just not the same. Many enjoyed the kitsch and many were one and done.
I miss the 'old' entertainment: a real chef preparing an appetizer such as local shrimp with yukon gold potatoes and sweet potatoes, combined with rich butter and heavy cream and served with wine at the Beach House for a nominal price, while back at the resorts the castmembers 'baby sat' your kid while having a program for little kids during the same time period - instant date night maybe only 1 and a half to 2 hours, but much appreciated. Older kids could go to the movies in the resort bus with another group of castmembers.
There was also a dining event you could have in a villa with a kitchen. My last one got cancelled when this program got discontinued.
Substitutes for the above: happy hour at Poseidon, followed by dinner there or somewhere like (insert current favorite). There are many great places.
Arrive with car - day trip to Savannah or Charleston, both of which are fun as well as historical and touristy and decorated beautifully in December. Don't eat at Paula's, it's a mess now. Do buy some pralines. Skip the boiled peanuts unless you grew up with them and already have a developed taste (not me). Take a carriage tour in Charleston but not in Savannah. Do a ghost walk in Savannah.
Go golfing! Play tennis. Do a boat thing such as fishing or dolphin watching.
Learn about war and the cr eation of Hilton Head from mosquito infested swamp to desirable destination. Touch on Gullah culture. I would say 'buy a sweetgrass basket' but not sure you would find them except in shops. Used to be everywhere you went on the side of the road.
Visit the Coastal Discovery Museum. Check out sea turtles which nest on HHI, just not usually in December.
Ride a bicycle. Walk a path. Over behind the Kroger is a lovely park with some nice walking areas and small ponds where you can find water birds and maybe more. You'll also find a community Xmas tree in December where I see loads of people taking family photos. There's a breakfast place here called The French Bakery, not to be confused with Social Bakery closer to the Disney resort. It was good both times I ate there. But busy.
There are spas as well if you want to get away a bit and pamper.
And, also there is Sea Pines with it's fake lighthouse. Looks real enough to me. There's a real one inland in Leamington that is not advertised much. It's not a working light and can only be viewed from outside, and there's only roadside parking now. You go past the Disney Beach house to the next check point and ask to get in to see it. Usually they will give permission and a leaflet. Return the way you came as exiting to 278 from Leamington can be ticketed. Keep your eyes open as you try to find it and I suggest this mostly for people fascinated with lighthouses.
https://www.hiltonheadlighthouse.com/?utm_medium=local&utm_content=Lighthouse
That's all I got right now. Well, except after you cross into the resort and park your car, walk back to the water and enjoy jumping fish, possible dolphin and lots of shorebirds with occasional Otter..