After asking many questions here about various destinations that would suit two of us, out of Miami, for early 2020, I've decided on Merida. I've not been there in ages, since I took a press trip focused on the new development along the "Mayan Riviera" near Akumal (Huge development, forget the name now).

So..about to book a house that looks to be about 4 blocks west of Santa Lucia Park, on or near Calle 74. Gets excellent reviews on various sites.

Any tips for me about the area? I will surely look to rent a car with driver for a few daytrips. Uxmal? Are there any cenotes warm enough to swim in January? Best beach for swimming on a day trip??

Anything I ought to be aware of before nailing this down? I'm very excited about going back. I LOVE Mexico and this will be sort of a new area for me...... Thinking already of cochinita pibil and all the rest!!!

Looking to fly direct from Miami to Merida, which I understand I can do a few times a week.

IMO, the Ruta Puuc (which includes Uxmal) is fascinating! And IMO, it's best seen with an overnight along the way. I loved the Flycatcher Inn, which still gets great reviews:
https://www.flycatcherinn.com
the Pickled Onion is also well reviewed and has been mentioned by a number of Fodorites over the years
About Us - The Pickled Onion

Thanks! Will certainly take in at least part of that route.

What about the proposed location of the rental? Good area??

The Ruta Puuc is great. We stayed a few nights at the Pickled Onion - it's still one of my favorite places that I have stayed anywhere.

I am not very familiar with the area around your rental. The area right around Parque Santa Lucia is great though - plenty of shops and restaurants, and then a few blocks south is the main square - so the rental seems to be well-located. A quick stroll on Google Streetview shows a few small stores and things in the immediate area, so that's convenient for getting beverages and things.

For beaches, we swam at the beach in Celestun, which was nice.

My familiarity is too outdated to comment. Good luck!