Yes, in 2008, the city got a bus line. It's called the V-Line. While it has a lot of riders, the routes are designed to get residents from housing areas to shopping areas. As such, there are 3-4 loops the buses make, but I can't say that it would be a way to get around town from hotels and B&B's. There are 3 stops downtown and the rest spread out across the city. Check the web-site before you come to be sure it serves where you want to go.
The Marketplace was the start of a development of shops around IN 49 and IN 2. Now there are numerous shopping plazas with too many names to remember. You'll find all the big stores "Kohl's, Menards, Home Depot, Target, Best Buy" and many of the smaller specialty shops that are common across the country. If it's crafts, 'Michaels' is here. If it's food, Aldi's will have it. Restuarants include McDonalds, Pizza Hut, Panera Bread, Gelsosemos Pizza, Coldstones Ice Cream, and other in the surrounding shops.
Valparaiso is a place that many have learned one way in and use it regardless of where they are coming from. With continued growth and construction of new roads, it can be confusing getting about town.
US 30 - access from the east and west - to the south side and much of the shopping districts
IN 49 - access from north and south - to the west side and more of the prime shopping.
To get downtown, you can use -- IN 130 from the west -- Washington St from US 30 -- Laporte & Lincolnway from US 30 and IN 49