My wife is looking at Traverse City, MI and the
Sleeping Bear Dunes park. It looks nice enough on line but the National Park map I've found doesn't give scale. Day hikes are what we're looking for. I just can't tell if there are 4-5 days of day hikes in the area. Anybody stay or visit up there?
In the back of my mind, I am thinking of going back to visit Estes Park, CO. That fits the bill for hiking and nature perfectly but for the fact that I'd have to make a stop to visit family in Denver and the long drive from here. And the budget...it will be more $ than MI.
Hee-hee. I spent my first sixteen years living within 90 minutes of Sleeping Bear Dunes, and the most recent eight years living within an hour of Estes Park.

(Two of the remaining eleven years were spent in Minnesota.) If you're looking for hiking, I wouldn't put NW Michigan as my primary vacation destination. That said, it's pretty tough to beat the SBD when it comes to a fun place to camp. As cheeba wisely points out, if you're looking for outdoorsy activities in that area, try finding stuff to do on the lakes. I'm taking my family to Charlevoix in early July, and we'll take a day out of our schedule to spend on Macinac Island. It's got an 8-mile circumference, and I'm sure we'll rent bikes for the circumnavigation, and take a few pit stops for hiking into the middle of the island. It's touristy though (lesserly-so than Estes Park, but not by a whole lot).
Shopping, fishing, golf, the beach -- these are typical summer activites in NW Michigan.
Sounds like you've got the Rockies all figured out. We're driving back to Michigan, but want to break things up a bit (visiting family in Omaha and Chicago, seeing Devil's Tower, Mt. Rushmore, the U.P.) for our own sanity. Also spending a few days in Edenville (the middle of the palm of Michigan), where we'll get in some power boating and kayaking and BB gunnery and fried-food eating.