When I went to Costa Rica, I flew into Liberia. Nothing special there, but you’re only about a half-hour from beautiful Tamarindo beach. Tamarindo is a very modern and safe area. All varieties of lodging available, and the town is very clean. You can rent surfboards for five bucks, and get lessons from pretty much any local.
While there, I highly recommend a jungle tour, ziplining, and my personal favorite – a day trip to Nicaragua (which also includes a tour of one of several volcanoes.)
* This is an airline sale that is time-sensitive. Plenty of alternate dates (even in other months), but you’ll need to book this fare before the sale ends.