Eat chifrijo. Eat patacones. Try some of the Caribbean food. Stop shouting, all of the Americans seem to be shouting there, it was the only annoying bit of the whole trip, such a tranquil place, then bam here comes a big loud American stomping through the jungle shouting. Same in the hotels etc. I'm sure there were nice normal Americans but you know, nobody got to meet them because you are put off by the big loud toolbags who are shouting a lot. They are everywhere.
it's good you are staying with a host family. Costa Ricans are cool, friendly people. If you are going out at night in San Jose ask your host family where to go out, specifically where not to go, you can get robbed at gunpoint pretty easily there if your aren't aware.