Section 120 was surprisingly very affordable. Bought three tickets for $130 for myself and my two sons. Granted, it was a night game vs. the lowly Houston Astros but it was still a Major League ball game. The seats didn't sit as close to the field as I was anticipating; you'll have to pay extra for those seats in the first 7 rows. We were in row 14 but still felt "close". 120 was right next to the on deck circle the Astros players were using. If you buy seats in the first two or three rows, you will be able to see what goes on in the visitors dugout during the game. (Not a whole lot if you watch MLB games on tv).

I live in Milwaukee but the main gripe I hear about Miller Park is how inaccessible it is to downtown where all of the dining, breweries and hotels are. I agree but it's only a 5-10 minute drive from downtown, on the same site as the old County Stadium. It's location is what allows for such amazing tailgating.
You can always just eat downtown at Brat Haus or Steny's Tavern and take their shuttle over to the park if you're staying downtown.
This is one of the most kid and family friendly ballparks you will see! Come visit the Brew Crew!