I'll definitely let you know my experience. We are going for two weeks (leaving next week!) Spending time in 5 different communities specifically to see if we would like to live there with the same kind of lifestyle you speak of. We are planning on using public transportation for the entire trip and will be everywhere from Alajuela to Dominical.
Back from our two week tour. Spent three nights in Alajuela - two too many! A very noisy area. From there, we took a bus to Grecia. Took a cab to our hotel. It was on the bus line, but since we weren't familiar, decided the first trip up should bring us right to the door. Loved the town! It had enough of everything - banks, restaurants, shops etc. We were able to bus it back to the hotel easily. Spent three nights there and then left for Manuel Antonio. The hotel owner gave us a better way to bus it than I had found on thebusschedule.com. We bussed back to San Jose, caught a short cab ride to the bus company going to Manuel Antonio. From there, we paid about $16 each for a bus ticket. The bus was not a/c - and we didn't have a window opening right on to our seats so it was hot, but not too bad. I saw our hotel as we drove by and hollered for the driver to stop. The bus was almost empty at that point. We only had to walk back about a block.
NOTE: if you are in this area - the park is closed on Mondays. We missed out on seeing it because I neglected to note that in my planning.
The hotel was a short 10 minute bus ride to the beach. Do not bring valuables with you - or you will have to take turns watching stuff. I recommend a waterproof pouch of some kind to tuck key and cash in that you can keep on you in the water.
From there, we journeyed a short way down the coast to Dominical. We arrived at the bus station and a driver offered to take us for $24. A splurge, but not bad. Dominical is a very small town. Looked like some nice places to eat - but we never took advantage of them. Our hotel was another $12 cab ride from town into the mountains - not accessible by bus. The place was beautiful and offered everything we could want - great restaurant, bar service, pool, view. . .
We decided rather than take the bus back to Escazu as originally planned, we would take a shuttle. Expensive compared to the bus ride, but we didn't have to worry about getting back to town and transferring later.
Spent our last two nights in Escazu - again very urban and noisy. We stayed at a lovely B & B off the main drag. It was only about a mile walk or a $2 cab ride to get to restaurants. The owner arranged for a nice local tour for our last day. Only about a mile further back into the hills, we were in a nice local community.
The only drawback to staying in this area was a $30 cab ride to the airport compared to $8 if we had stayed in Alajuela. However, we wanted to see different communities. Next trip - we'll spend only one night on either side of arrival and departure close to the big city. The rest of our next trip will definitely be on the coast. We loved it there! Once you get used to the humidity, the ocean and laid back communities are definitely a plus.