Went last year...I didn't stay by San Jose though, I was up in Guanacaste (landed in Liberia). More of a desert up there...and from what I heard, it's
not as nice as where you will be. The Volcano was cool, diving was decent (not great...water was cold and visibility was only 30 - 35 feet), liked the beach...we stayed at the JW Marriott up there.
I did go down to Montezuma for a couple days...was able to do some canopy tours, cliff diving, and a little surfing. Really liked it there. It's listed as one of the blue zones in the world. A canopy tour would be a must do if you're not afraid of heights.
If you do spend for a rental car, get the tire insurance. Many of the roads (at least where I was) are unpaved. I didn't get it...but I can see that it would have been very easy to get a flat, and if it's cheap, it's worth it.
Few pics...
Hope you have a good time...perfect days, every day.