You should be fine. There is plenty of parking though it's a decent drive from the hotel to the ball park-there is construction along the area. For places to eat, Milwaukee has some fine restaurants of all different types, this guide will help a bit http://www.expressmilwaukee.com/For places more unique to Milwaukee, there is Mader's for German food (and close to your hotel)http://www.madersrestaurant.com/For a bit lighter German food there is the Old German Beer Hall (also close to your hotel) http://www.oldgermanbeerhall.com/The Safe House is often recommend since it is unique http://www.safe-house.com/A bit further away is Three Brothers Restauranthttp://www.yelp.com/biz/three-brothers-bar-and-restaurant-milwaukee You are coming in the middle of the music festival Summerfest http://www.summerfest.com so you may want to check that out by the lakeThe Milwaukee Art Museum is wonderful in wonderful buildings right on the lake http://www.mam.org/The Zoo is top notch though it can get expensive especially if you pay for parking http://www.milwaukeezoo.org/Closer to miller park there is the Potowatomi Casinohttp://www.paysbig.com/And the Harley Museum http://www.harley-davidson.com/wcm/Content/Pages/HD_Museum/Museum.jspThere is the Miller Brewery Tour http://www.millercoors.com/milwaukee-brewery-tour.aspxAnd a Sprecher Brewery tour http://www.sprecherbrewery.com/tours.php And since you are right there you'll want to stop at the Usinger's store on Old World 3rd street http://www.yelp.com/biz/usingers-milwaukee
Hopefully this gives you some ideas. If you have other questions or more specific things you would want to do just ask Oh yeah, many outside of Wisconsin do not know this but carry ins are allowed at Miller Park if they follow the following rules:http://milwaukee.brewers.mlb.com/mil/ballpark/information/index.jsp?content=security