Just came back...
There is also a full hookup private campground just outside the north entrance - not ritzy, but not a bad spot, either. We tented there about 4 years ago. That's when we decided to move up to an RV - not because of the campground, but because of the tent!
There are many others a little ways away - we stayed at Stoney Point Resort in Cass lake (about a 45 min drive from Itasca) this past two weeks.
Many long, paved bike trails in the area - Paul Bunyan, Heartland, etc., so bring the bikes, also!
Also check out Bemidji State Park, just north of the town of the same name, about 1/2 hr from Itasca.