I spent a month in Jaco in Jan/Feb this year. I found it to be a nice middle ground where it's on the beach, but is also a (small) city with reliable internet. It's easy to get to Santa Teresa/San Jose/Manuel Antononio, etc as well.
It has a (not-entirely-undeserved) rep as being seedy/a party town, but I found the overall pros to outweigh cons related to that.
I find that whole garabito zone to be WAY TOO HOT. Like it's really dry there. The guanacaste region too gets really hot and dry. Somehow I think my health prefers hot and humid. My nose is all dusted up and clogged in those regions. That said this country has a TON of microclimate stuff going on, so there's something for everyone, because plenty of people don't seem to mind that at all!
It has a (not-entirely-undeserved) rep as being seedy/a party town, but I found the overall pros to outweigh cons related to that.