In my opinion, Costa Rica is as safe as any other place. Certainly politically. There are no worries about the Federal Police harassing you because you're a foreigner. Of course, there are bad guys just like any other place, so you don't want to be a fool. If you're staying at some sort of resort, the kids will not only be quite safe, but probably isolated from the true culture. It's a pretty poor country, and if you venture out of San Jose and experience local dining, you'll find inexpensive, yet tasty meals, that are mostly based on beans and rice, and often a hunk of meat, probably chicken. The local Fruit will blow your mind, as in any tropical place.
And, fortunately, you probably won't be lucky enough to see that goliath tarantula.
Bonus, you're Gas Gas 250 is a viable streetbike in CR. for that matter, so is an RM 250. You'll probably lose count if you try to see how many Yamaha Serows you can spot.
Also, you can go to Volcan Irazu on a tour, and see both coasts at once from the top. It's the tallest peak in CR.