This hotel located about 10-15 min drive away rom the SJO airport (not in the city of San Jose) offers one day tours, incl. 12-HR long Arenal with hot springs: https://www.adventure-inn.com/tours/ . There are other tours from there, too. We stayed at that Inn a couple of times, but did not use their tours, so decide and research if it is smth that might appeal to you.
We found Arenal beautiful and would recommend staying there, if your time allows. Even the drive there was pretty. We stayed at https://www.arenalobservatorylodge.com only <2 miles away from Arenal, great views and trails right there.Edited: 18 February 2018, 02:50
Thanks! I'll check it out.
I did a day tour to Arenal from the SJO area years ago. We left early, spent a few hours at Tabacon, mostly drove and stopped and drove and stopped in the tour van, an got back late, exhausted and wishing that we had slept closer to the volcano. Everyone on the van with us felt the same way. This included some families that had made the mistake of spending their beach time at Jaco.