Remy is magnificent and if that is where you got engaged, I would definitely do it again!
If you don't like the cruise food, I don't think Palo dinner and brunch is overboard. I believe you have to be in a Royal Suite to have Palo delivered. I would e-mail or call shoreside concierge to confirm.
Mixology - yes!
Excursions - Stingray City is pretty cool! If you want to save some money, you can also just get off the ship, hop in a shared taxi and go somewhere on Seven Mile Beach (we went to Royal Palms Club on our stop in Grand Cayman)
We stayed on the ship in both Cozumel and Falmouth on our cruise last week. We enjoyed a less busy ship!
Skip the couples massage. We've done it and it was subpar and too expensive, IMHO. I can get much better spa services at home, so I skip Senses when sailing
DCL. Save your money and just get the Rainforest pass OR simply go in the hot tub on the concierge sundeck! We had it to ourselves a few times on our last cruise.
Skip the Cabana. We've done cabanas twice and opted not to do one on our last cruise. We had zero issue finding great loungers with shade. Go to Serenity Bay, find a place in the shade and enjoy the beach!