Hi, I am not sure which blog you are referring to. I'm guessing it was Valley Lane? We were out there last year. We haven't been out there this year yet. With all the rain we've had I'll bet there are a few very muddy places because even when it seems fairly dry the trail still has a few muddy spots to navigate through. It would be nice if they would make some improvements to the trail by putting stepping stones or planks in some of these places. Maybe they have made some improvements since last year but I would wait for it to dry out a little bit before we tested it.
If you are referring to Fort Rock, we've already been out there multiple times this year. With the ages of your kids I would recommend this one highly. You can print the map and pick your trail and you can make adjustments once you are out there if you want to go a little longer or shorter. Don't forget your bugspray though! My kids are 9 and 11, but we've been doing these trails since the youngest was 6 and they still love them!
I hope that helps! If you come across any trails that are local that aren't already in my blogs, I would love to hear about them! Have fun!