Until I get a chance to do my trip report, I'll give you a bit of info. We stayed for 5 nights at Casa Altamar near Tankah Pueblo. https://casaaltamar.com We loved it. The views were amazing and the food excellent. A continental breakfast was included, with other options possible for a fee. However, the continental breakfast was plentiful and good, with several types of fruit, toast, and banana bread. You can purchase lunch and drinks on the beach, and the restaurant is open for dinner. They serve complimentary cold water on the beach, too. The beach is quiet and uncrowded, even though there is a beach club that is open to the public (for a fee). The beachfront section specifically belonging to the hotel is small (but more than adequate for the number of guests--loungers were always available), but the beach itself continues in both directions for a long way. There is a dock that extends out past the rocks, with steps down into the water and hammocks under a palapa at the end. There is also a pool beside the hotel, right behind the beach.
For 4 days, we didn't miss having a car, but be aware that taxis into Tulum are expensive (400 pesos one way), and tours will usually charge a bit extra for pickup there We paid 100 pesos extra for our Sian Ka'an tour with Community Tours. (Recommend! https://siankaantours.org ) That was far less than a taxi, though.
Note: We used this company for a shuttle from the airport to our hotel: https://www.cancunairporttransportations.com It cost less than the shuttle the hotel would have arranged for us, and it was okay, although meeting up with them at the airport was a bit of a zoo. The one the hotel books might be a little more luxe, and they might meet you with a sign with your name on it, whereas this one required us to find the agent in an area with lots and lots of travellers and agents for other shuttles, etc., milling about, but it all worked out. (Cost was $116 US, including two bottles of water.)
We took a taxi to Tulum to visit the ruins, but other than those two activities, we pretty much stayed at the hotel. If we were there longer, we'd probably have wanted to do additional excursions, so you would need to factor that in to whether you'd want to stay at Casa Altamar and whether you'd want to rent a car if you did. There is not a lot to do other than the beach and pool. Our first day, we spent a wonderful day at the beach and did some snorkelling. (Snorkelling is okay around there, but not spectacular. It was a good place for us to get used to snorkelling again, though, as we don't get to do it very often.) We planned to spend our last day at the beach, too, but our last couple of days were very windy and sargasso piled up at the beach. That would be true of any of the hotels right along that coast, mind you, but some might be closer to alternative activities. What we did that day was walk to the very close by Casa Cenote, and we snorkelled there and saw the resident crocodile, Panchito. Then we spent the afternoon at the pool.
So, for us, for four days, Casa Altamar was perfect and we were happy not to have a car. (The way people drive there stressed me out, and I was happy to have people who were more used to it driving us.) We loved that the beach was quiet and uncrowded. Some of the places I'd looked into closer to Tulum, in the hotel zone on the beach, had reviews that mentioned loud music blasting all day. We wanted a quieter experience, and we got that at Casa Altamar. (They play music, but not loudly, and their restaurant and bar closes at 10 pm.)
Hope that helps!
Oh, also, note that there are no televisions, if that matters to you. Also, it's not uncommon for the Internet to be spotty and for there to be brief power outages. Based on the reviews I read, this is true of other hotels on the coast near Tulum, too.
