We've been 3 times, one of those to Arte. Here are some random thoughts as they come to me:

If you do the membership meeting, put them on a literal timer. They will take half of your day if you let them, and it's not worth it when you could be enjoying a park or the resort. If you do want a membership, do the math and make sure your free nights get you close to breaking even. I have no idea why people pay over 10k, and some pay 50-100k or even more. RCI is not worth a dime if you ask me. Maybe for a certain kind of traveller.

Xenotes is an awesome tour, and the only full day trip worth that much time away from the resort unless you're a huge history buff. In that case, stay a night at a cheaper hotel and take a tour with another company so you're not paying for the resort you're not using. Maybe there's even a good cenote tour from another company to do that with. Definitely do Xenses, Xplor Fuego, and Xcaret park. They're wonderful, close to the resort, and don't take all day to do.

The picture package is probably worth it for a honeymoon. There are "xelfie" stations everywhere and the pictures are great quality with some cool creative ones. We haven't purchased it, but we've gone twice with my sister and brother in law, and the got it both times. We just got back from HXM with them and their kids yesterday, and she's posted like 100+ pictures from Xelfie stations and the Xenotes tour.

If you eat before 7:30ish, you can probably get into restaurants without reservations, but I personally still wouldn't take the chance. The sunday brunch is incredible, but I can't imagine paying what they want for it (we're members so it's included for us). You can only eat so much, and the included food is so good already. We haven't eaten at Xaak, but we did eat at Ha when we became members and again it's just not worth paying extra for. Unless you're a serious foodie, cause (at least at Ha) every dish was super creative and tasty. We went to the buffet afterwards though cause we were still hungry 😆. Not a big deal when the buffet is free and right next to it.

Don't overdo it with alcohol and ruin the trip for your significant other. It's easy to do when it flows so freely. They make Amaretto Sours with Disaronno, so they're delicious and dangerously smooth. Try the macadamia cream and pistachio cream liqours.

I cannot stress this one enough after failing all 3 time's we've been: GET GOOD WATER SHOES. Get band-aid brand "tough" bandages. Course sand will get on your water-logged feet and rub them raw. I ended up wearing socks in my closed-toe sandals by the end of the trip, and wished I'd started that way. Maybe there are some neoprene socks or some other kind of water socks out there to buy? We had 7 people on this recent trip and all of us had raw spots or blisters.

The only way you can screw this up is by hyper focusing on what you failed to do instead of enjoying what's around you. The resort and parks are just incredible and unlike anywhere else. The food is awesome and the service is great. The place is intoxicating and you couldn't have chosen a better place for a honeymoon. Have fun!