Grand CA is fancy, but not overly Disney. Kids would probably prefer the Neverland pool at DLH over the unthemed pool at Grand CA for instance (no, can't use the DLH pool, if you're staying at GCH). Then again, 12 and 14 may prefer the "coolness" of GCH over the kiddy-DLH.
Knott's used to be nice. It is in a transition period between undermaintained theme park, and undermaintained thrill park. Couple unique coasters, some older rides that have an almost Disney-like charm (Calico mine train and Log Ride), and lots of lesser thrills. The atmosphere is nothing close to what it used to be. Hope you aren't paying more than $25 per adult. It certainly isn't worth the $45ish gate price. I've got 3 coupons with that price, and last year you could get tickets at one of the local grocery stores for $22ish.
Crowds will be "not great", especially on the weekends. Get to the park before opening and do as much as possible in the first couple hours, especially on the West side (Adventureland, Frontierland, New Orleans, Critter). West side is the worst for traffic later in the day.
Plan one morning to do the West side. Plan another morning to do Fantasyland-Toontown.
Once crowds set in, use the heck out of FastPass, use this time to ride the rides with shortest lines(Casey Jr,. Canal Boats, Alice, Snow, Pinoc) hop over to DCA.... Avoid mainstreet during the parade, ulness you want to watch the parade. BY ALL MEANS, avoid mainstreet right after fireworks.
Great Fantasmic! plan: As the first Fantasmic! starts, hop the train from anywhere into New Orleans station. Hang out around the back of the crowd until after fireworks. Once fireworks is over, you can easily get the front row/center spot of your choice, and you won't have to wait 10 hours like the people who had front row center for the first show did..
If you want to catch fireworks from the best location, grab a spot just South of It's a Small World.