Try the area northwest of Newberry. Some single track, tons of easy two tracks, sno mo trails etc. I took my family up there Memorial day weekend - had a great time. The ORV trails are easily ATV compatible - one of my kids and my wife are on quads and had a great time. Once i get home I can double check which camp ground we stayed at - but the ORV trail comes right into it, plus some other specifics not coming to mind right now. One down side with the two tracks is they were all on section lines, so straight and (to me) boring. THe up side with that -almost impossible to get lost!
A plus with that area is it is very close to Taquamenon (sp?) falls - not far from Grand Marias, or Newberry, head over to the Soo Locks perhaps.
But...my preference for a real UP trip would be the west side. Partic. up in the Keweenaw., but Marquette is a beatuful area...also Ironwood...also...aw heck..its all beautiful up there!. Hey get Nick Zambon or Magoo to weigh in here ...they are real Yoopers... I am just a former Yooper Transplant!