Casa que Canta in Zihautenejo has beautiful weather from late Nov or early Dec through March. It is a small resort for adults ( no children under 16). It is not on the beach but on the cliff next to the beach ( 5 min walk) with gorgeous views, good food, and many rooms have private pools ( the way to go). The old Villa Del Sol is now the Viceroy. It was nice previously and did not allow kids below 16 in the early days but it seems that has changed when the owner built condos on the hill and allow them to use the beach facilities. Worth it to ask, but it has become a very large property - in a great spot on the beach - but we have not stayed there in the last 20 years as we find Casa que Canta much nicer. Casa que canta I can highly recommend. If you are interested pm me and I can tell you about it. It is not as luxurious as an Aman or someplace like Trisara, but it's pretty darn nice if you want to get away, have some privacy, relax and enjoy good weather this time of year. I would say depending on the room it's luxury but done in the mexican theme with some lovely little touches. my husband and I have been going on and off for the last 20 years. The walk to the beach is 2 min. And if you want to rent chaise lounges there are a number of places where you can spend the day on the beach if you want. We just got back last week and had lunch at the Villa del Sol, now Viceroy a couple of times and did see younger children around but not too many. It was not intrusive but led me to believe more open to families now. It is on the loveliest part of the best beach - La Ropa. Not sure how the rooms are these days however in the now viceroy and it pretty big. Do not go during Easter as the beaches are very crowded. Do not go during the one big annual town festival as it's noisy ( usually in feb or March you can ask the hotel). Do get a pool suite either in the luna building, or one of the high end suites one of which is the owners suite. They also own two 4 or 5 room villas and rest those rooms if the villas are taken. Those rooms are more modern and the villas are on a corner of the beach - a 30 second walk. One caveat, there are lots of stairs in the main hotel so if this is a problem may not be for you.
There is also supposed to be a lovely very private hotel north of punta mita called Imanta, but I have not been. I find the Four Seasons Punta Mita to be very family oriented. Lovely location, but lots of kids and quite large and busy although that might change if non vacation season.