I've always gravitated to the front with my kids as I find they are more engaged (and inclined to say the aloud prayers aloud) if they can see what the priest is doing on the altar. I just cast my mind back to being a kid and remembering what it is like to stare at the backs of all the huge adults.
The only times I get annoyed at parents over the kids behavior is when a parent doesn't take a crying baby out of Mass - and the kid keeps crying and crying. One family has twin boys about 4 or 5 who run out of the pew and sometimes on the altar... and the priest encourages the parents to let it go as it is "their Father's house." I've seen these kids in the local supermarket and they run around wild there as well.
I'm sure your kids are fine! I'm just happy to see families at Mass, to tell you the truth.