Agree with mlgb - if you are driving to the Osa, you definitely need to stop at Savegre - wonderful quetzal and hummingbird photo ops, gorgeous valley. Also for some very easy shots of the fiery-throated hummingbird (not at Savegre), stop by Paraiso del Quetzal signposted at the 70km marker on the Inter-American.

I haven't gotten as far as planning the drive from San Jose yet so I appreciate the advice.

I thank you all for your advice. Unfortunately, I won't be making that trip after all. Because of some health conditions and the medication I take for them, my doctors don't want me anywhere in Central or South America (or Asia or Africa) again. Instead, I'm going to spend some time in south Florida at the same time, trying to find birds and wildlife to photograph.