Heading out on vacation pretty soon. A small little trip to Bryce Canyon and Zion National Park in fun and exciting Utah. Both Erin and I are looking forward to this trip in that it will be a nice, relaxing break for both of us. This adds to the list of National Parks that Erin and I have been to.
- Grand Canyon National Park
- Badlands National Park
- Mount Rushmore National Memorial
- Yellowstone National Park
- Lake Mead National Recreation Area
- Sunset Crater Volcano National Monument
- Mammoth Cave National Park
- Jefferson National Expansion Memorial (St. Louis Arch)
- And many, many parks in the Washington D.C. Area
Did I miss anything?
John Telford 
You forgot Sleeping Bear National Lakeshore
Actually, I don’t think I have ever been there. Also, it is technically not a National Park but a national lakeshore. There is only one official National Park in Michiga, Isle Royal.
More details can be found at http://www.nps.gov/state/MI/.