http://www.graygooseinn.com/
Gray Goose Inn, quiet little country inn in downtown Chesterton, short drive from Beaches and Indiana Dunes State Park. World's best innkeeper(yeah, I've known him for a long time), delicious breakfasts, tasty snacks, Pretty lake view rooms, etc. Nice solarium with lake view, wood floors and fireplaces in three suites. I recommend the Gray Goose Suite, as it has the best view. There are no pools there(eight room country inn), but it's near the water park, and beaches. Four Diamond AAA rated.
You can take the South Shore if you want a care free vacation, or drive, as it's close to Chicago. Local foods, European Markets on the weekends.
Several kid friendly parks including water parks in a short driving distance. Several theaters and an outdoor Mall nearby Michigan City.
Not too sure if Kenosha WI is too far for you, but the Bristol Renaissance Faire is going to be in full swing on the weekends during that time frame, and there are some hotels nearby that might give you insight on more to do during the week.
Hope you have fun wherever you go.