As the OP said....it is huge

Every store you could imagine is there! Shopping heaven
Well first....where to stay. There are plenty of nice hotels in the area. I've stayed at the Holiday Inn on Appletree Square which is really close to the Mall. It's a nice hotel with an awesome health club!! However, with young kids I would suggest the Country Inn and Suites
You can see in the picture it's literally right next to the Mall....very convenient. But the rooms are bigger and it gives everyone a little more space! It's located at 2221 Killebrew Drive, Bloomington, MN 55425 and the phone is (952) 854-5555.
As far as the Mall itself goes....there is a ton to do. I'm not sure if your main goal for going is just for your children's entertainment or if you plan to shop. However, there are two main attractions for children: Camp Snoopy and Underwater Adventures. Camp Snoopy is a neat indoor theme park with quite a few rides. If your kids like rides, I would just get the unlimited wristband for $24.95. GO here:
http://www.campsnoopy.com/default.asp for more info.
Underwater Adventures is neat also...but you should check out their web site to see if it's for your crew:
http://www.sharky.tv/info.html
I guess I would say to spend two days at the mall, maybe three if you're planning to spend some time shopping too. Even with two days you won't get around half of it
As the OP mentioned there is the Minnesota Zoo in Apple Valley. This zoo is neat....the dolphin show especially! The zoo is worth seeing I think. (
http://www.minnesotazoo.com/) Also, ValleyFair is over in Shakopee....I guess it's our version of Six Flags

Probably not worth the trip if your kids don't like roller coasters--stick with Camp Snoopy. Here is the site though:
http://www.valleyfair.com/public/inside_park/rides/kids/kids.cfm
Hope this helps...have fun!