Ditto the others.
The flights are perfectly fine. I haven't flown to CR out of LAX, but at MIA the check in process is at best inefficient and confused. AA may handle more passengers, which can be an equalizer, but while TACA has fewer flights they seem to schedule them all around the same time. Get there at LEAST 3 hours ahead, bring carry-on only if you can do it (not because they'll lose it but for reasons that will be apparent below) and have PLENTY of patience. Latinos have a different attitude about time, so you might as well get used to it before you leave. You may go straight through, but it ain't worth taking a chance. One thing I would add is make sure you get in the right line and don't be afraid to ask.
Expect to see lots of large family groups with humongous luggage (that you might have to manouver around) yammering away in spanish. It can be somewhat confusing for a gringo that hasn't been through their process before. The first time I went, I saw a huge line that stretched around the corner. I went to what I thought was the end of the line. It took me 10 minutes before I realized why the line wasn't moving. It was a "luggage line".

There were people in it, but they turned out to be family members watching the luggage, while mama or papa waited in the main line. Then when they finally got to the front, everyone would go back for the luggage and drag it past everyone waiting in the regular line.
It made some sense because there was so much luggage it would take up too much space in the main line and would be a hassle to pick up everything and move a few feet every few minutes (though many people used that method as well). Instead, some people preferred to have papa wait in line and mama watch the luggage, while the grandma sat comfortably and the K*ds ran all over the place back and forth between their parents and then manuever all their bags under the rope barriers and around the other people waiting in line when papa got up front. Yeah, that's a lot better
Lets just say check-in can be a bit chaotic. It seems almost humorous now, but at the time I was ready to pull my hair out.