We are staying on board too ! Nothing on the Celebrity shore excursion list seemed appealing. Much rather have some time in the hot tub ! Maybe a walk around the pier for some exterior shots of the ship.
You only have 3 choices is Casa de Campo. The ship docks at a pier that's not next to ANYTHING but empty fields. It IS right across the river from a very nice old smoke-belching foundry though!
• The marina - big new condo village around a marina- shops and restaurants. Usually they have free shuttles from the ship.
• Alto de Chavon - a recreation of a Mediterranean artist's village. Cobblestone streets, timber and stone buildings. Lots of craft shops and reataurants. Also should have a free shuttle.
• The ampitheatre - big local folkloric show with LOTS of dancing.
I did the marina and craft village and was back on board in 2 hours. The price was right.