We went a few years ago on a familyt trip. Didn't fish, but I'll offer any help I can.
We rented a nice house in the hills above Potrero. Nice modern house with live-in care takers, but not walking distance to the beach (or anything else). Every morning and every night we'd have to bump down and then bump back up and old dirt mountain road. It was nice though from the perspective of having family time. We stayed in and made our own dinner most nights, hung out by the pool, had cocktails and listened to music.
A couple of the days we went down to Playa Flamingo, which is a nice beach with a few amenities, but isn't too touristy. One day we drove over to Tamarindo which was much more touristy (and not as nice of a beach). They also have a bigger grocery store there so we were able to get more stuff for the week. My wife and I went to one of the zip-lining places one morning, had to bump along a mountain road for about an hour to get there.
We did a day trip up to Nicaragua. Nice trip but it was a really long day. Crossing the border into Nicaragua (and back to CR) wasn't the easiest.
All in all, it was a nice trip and very relaxing.
