I've really enjoyed your RR and am looking forward to reading the upcoming installments. If you go back north I second the motion to visit Arenal volcano, there's a hot springs place there too, which was really relaxing, and to check out the Nicoya Peninsula. Stayed at a great little hotel there a few years ago, set back a few yards from the beach in the jungle. Had a great time there. One caution....if you ride the Panamerican Highway north out of San Jose and into the mountains, there are lots of twisties, but also truck traffic (at least when I was there 7 years ago). Came around a blind curve only to find that some truck had dumped it's crankcase all over the road. Could have been a game-ender as there was no guardrail or anything else to stop you from falling hundreds of feet straight down.
Wishing you all the best on your continuing journey!