Go see Manuel Antonio. Yes it has grown and yes it is a tourist destination but it will only get worse. Make sure they stop in at El Avion for a unique drinking experience inside a C-123 used during the Contra re-supply missions into Nicaragua.

If at ALL possible, try to avoid ANY Pacific beach town during Semana Santa (26 March - 04 April) -- waaaaaaaaaaaay too many people.

There is a newly opened toll road that runs from near the airport to Jaco -- cuts at least an hour off the old road and is (as of 3 weeks ago) still pot-hole free.

Arenal/Tabacon and Monteverde all get +1s from me as must see while in CR.