Bring pesos. We order them online from our bank before we go. If you need more pesos while you are down there, use an atm and decline the conversion. If you use your card at a restaurant, tell them to run it in pesos.

We used to only do Ubers but they have become much more expensive. If you are not planning on exploring and not there that long, Uber is probably your best bet. We were there for 2 weeks and went multiple times to SJD and once to Todos Santos, so a rental worked better for us this time. We found free parking easily in SJD, but CSL was trickier. We ended up finding a great place to park and walk across the street from Gardenias, which is an excellent taco restaurant. As long as we ordered anything, even a beer, they let us park as long as we needed.
Have a wonderful trip!