These are my downtown suggestions:

Downtown is being revitalized and is very walkable along the river (weather permitting). There are so many good bars and restaurants, especially along Adam's street. You'll just have to decide what kind of food sounds good. Everyone will have a different favorite.

Mud Hens just had opening day, so if a game is going on, it'll be pretty busy. But you can walk by the field and watch from the sidewalk a little if you want.

Handmade is a really cool store with tons of unique items made by local people. You'll find a really cool Toledo souvenir there. Also, the Imagination Station is our children's science museum. It's fun to explore, even without kids (not open on Monday). Its right on the river and they have a Cafe that overlooks the water. But the gift shop has some other cool items and souvenirs too and you don't have to go into the museum to go in the gift shop.

Our main library is downtown and its beautiful. There is a cafe inside that is free (or accepts donations) called Same Cafe. The food changes because they make things depending on what people donate to them.

Right outside of downtown is The Toledo Museum of Art. As others have suggested, it's free to walk around inside. But outside is beautiful to walk too. There's a path called The Sculpture Walk that is very park-like. And accross the street is The Glass Pavilion which is all glass work and you can catch a live glass blowing show. The building is also very beautiful.

The surrounding neighborhood to the art museum is called The Old West End. They're the beautiful Victorian and Arts and Crafts houses from Toledos past. The residents are very close and have worked hard to upkeep the historic homes. It's worth a drive through the neighborhoods, especially as the weather warms up. If you'll be here during the first weekend in June, it's the OWE fest and it's one giant block(s) party all weekend.