We did a similar trip a few years back. (Pre-Covid) Our hotel for HW was about 45 min away from the park. (Seemed the only decent place at the time of booking) We did HW hit up dry side first thing then headed over to the waterpark. And it seems that everyone else had the same plan. So we were stuck with long lines for the coasters in the morning, then long lines for the slides in the afternoon, then again long lines for the coasters in the evening. We left the park and drove to our hotel right beside KK.
The Crown Plaza next to Kentucky Kingdom offers an awesome 2 bedroom suite that is great for families that are traveling together. Has a living room in between both of the rooms. Highly recommend (We traveled with another family as well, and it was awesome) The waterpark at KK is definitely worth the visit. (If you can drag yourself away from Lighting Run) If you have two families going I'd highly suggest a cabana. It was great for our visit, and when you split the cost between two families it's not bad at all, and makes for a great "landing space" for everyone.
I hope you have an awesome trip, and enjoy those water coasters at HW, they are amazing!