Welcome to the forum and the RV lifestyle!
Our family has no experience with Keystone, but did own a 2006 Jayco Jay Flight 27BH that we loved and towed more than 40,000 miles. The layout and storage were well-designed, and the trailer held up well for the more than 10 years we used it. That was prior to Thor's acquisition of Jayco so, honestly, I'm not sure how much my opinion is worth at this point.
One suggestion I did want to share with you . . . Give some thought to the size of the bunks and the storage around them. Your little tykes won't stay little for long, so be sure they won't outgrow their bunk space during the years you plan to use the trailer. Our Jayco had a narrow top bunk and a full bottom bunk. We started out with our older child on the top bunk for safety reasons but, eventually, he outgrew that bunk as he moved into his teen years. Luckily, by that time, our daughter was old enough to use the top bunk safely.
Since she has a petite build, she never outgrew the smaller bunk. But, if both of our kids took after my husband in size, it would have become very uncomfortable for one of them at some point - something we hadn't thought of. Also, having storage space near the bunks for not only clothes but their personal possessions, as well, will go a long way toward keeping the living area of your rig clutter-free. Well, mostly clutter-free.
Good luck with your decision, and best wishes for many years of happy family camping ahead! Buying that first trailer was one of the best decisions we've ever made.