Didn't realize you were traveling with kiddos. Now some of your "security" concerns and questions make a bit more sense. Looks like a rad trip, I'm jealous!
areas of CR that I've enjoyed:
Volcano Arenal (waterfall repelling was super fun)
Dominical (little surf town with some expats living there)
Puerto Viejo & Punta Uva area on the Caribbean side, has a totally different vibe than the rest of CR, felt more jamaica'ish
Quepos and Manuel Antonio was just OK for me, the park was nice but I didn't think much of the Quepos