We've stayed at Hotel Ixchel and Playa Arena both on Playa Norte, Ixchel is the nicer of the two and would be reasonable for an anniversary but it's not super nice by any means. We have friends that regularly stay and love Hotel Secreto, the only thing that has kept us from staying there is the beach immediately in front of the hotel is very limited and somewhat rocky, but also very private. But you are blocked from walking on the beach to other parts of Playa Norte, but could walk/golf cart to a beach club if you wanted better beach. Villa La Bella would be another one I would consider, though more rustic its a really awesome setting and they have a great bar worth visiting regardless of where you stay, hotel might not be 20th anniversary quality depending on your expectations.
Def do the golf cart, beware they do create DWI checkpoints, especially at night so don't drive with an open container and you should be fine, or bring an extra $100 to pay the "fine". I'd take a cab if going off Hidalgo for dinners at night.
