We always go up north (Lake Gogebic) on Columbus Day weekend (second Monday of Oct). We have never been disappointing in the color at that time of year, in many cases it hasn't hit peak yet.
Per John's Journal (all dates are Oct unless otherwise noted)
2008 - Peaked between the 8th and 12th
2007 - Maples peaked in Late Sept, rest in early Oct, Oct 14th was past peak
2006 - Nearing peak on the 8th (no other mention of color after this)
2005 - Peak around Oct 10th
2004 - Entry on the 8th expected peak around the 10th to 12th
2003 - Between the 9th and 13th - fast change that year
2002 - Between the 11th and 13th
2001 - Expected the weekend following the 4th
2000 - Journal entry does not pull up
1999 - Not enough detail
My personal experience has been that colors change in the UP is geographically diverse. If you don't like the colors in one area, drive somewhere else, they will be different. Bottom line there is nothing better than waking up on a cool fall day in the UP with a color show going on. The 3-4 weeks of late Sept to Mid Oct provide for some great experiences in the UP.