I am out there a couple of days a week, but it has been ages since I've been to the main part of the park. Dogs are very welcome in the campground and on the back side of the park where the shows are, but you probably would want to leave the dog at the campsite if possible on the day you go to the museums. All of the museums are a lot of fun, as is the parade of breeds. It's also really neat to see Man O'War's grave. I always enjoyed the Draft Horse Barn as well. I am not sure if they are running the horse drawn tours right now, they've been a bit funny about that in recent years. Since it is peak season they may be back running, I know during winter they use a tractor instead. In normal years you would be almost guarenteed that there would be a show of some sort being held at the park, but since WEG is coming all of the shows past a certain date had to be canceled this year.
Also be prepared for a lot of construction as they are working madly to get everything done before WEG. It looks a hundred times better than it did this time last year, but still is a bit of a mess in some parts. (The tourist part of the park should not be affected much).
The new outdoor stadium came together nicely and is rather impressive, and they've completed the new indoor too, but they usually keep it locked so you probably can't go explore the inside.
You will get a sneak peak of some of the marathon obstacles being used for WEG, as most of them have now been set. I don't know that you'd want to go out on the course to get a closer look, they like to keep people off, but most you can see from the roads. If you can take a look at Mount Mick, it is amazing and is located in the field directly across from the campground. You'll see a lot of white rope in the cross country fields, that is where they have roped off the galloping lanes for cross country and marathon.
Have fun, I still remember the first time I visited the KHP when I was here on vacation from CA, I had no idea how big a part of my life it would become back then! Although the trail ride concession is not that impressive, it might be worth taking, the first time I rode at the horse park was for a dressage clinic and I remember being in awe of the fact that I was riding at the KHP! It was a great feeling