we like imagination station - we have a membership and my dd requests a trip at least once a week.
The zoo is another great choice. The Toledo Museum of Art has a family center with art projects. You can look it up on their website, but *think* it is Tuesdays, Thursdays, and Sundays. The family center is free but parking is $5. The church adjacent to the museum has a sign in their lot saying that parking is reserved for church goers and art museum patrons, so we always park there b/c it is free.
There is a Holiday Inn (I think) in Maumee near the turnpike with a small water park in it. In Perrysburg the Holiday Inn French Quarter has a pool and get away weekend deals - i know ppl locally check in there with their families in order to have an inexpensive vacation.
There is a hotel downtown next to Imagination Station but I can't remember what it is - I'll bet if you called they could tell you. I'm sure it has a pool.
There are several Metroparks that are wonderful for spending a day - many have hiking trails, play grounds, flush toilets with running water, and grills for cooking.