How about an alternate route? You could reach Maine from Detroit by going back through Canada to western New York State, then via Buffalo, Rochester and the Finger Lakes, Cooperstown, through the Catskills to Albany. Maybe detour down the Hudson Valley a bit (or all the way to NYC if that was part of your initial itinerary). Cross through western Massachusetts - Tanglewood in the Berkshires - to the greater Boston area and then up to Maine. Or up to Saratoga Springs and cross through southern Vermont and New Hampshire. All of these have plenty to recommend, in that lazy, see a bit of this-or-that way of a summer drive... mountains, lakes, wineries, some art, music and even horse racing...

Perhaps you've done this before, but it seems that from Ottawa, you're probably more familiar with the northern route!

Thank you so much! We have been to the finger lakes but don't think to Buffalo or Rochester .. definitely not to Cooperstown .. Albany .. .lots of time spent in Boston .. hmmm you've got me thinking! Tanglewood in ther Berkshires??

Glad to help turn your itinerary on its head!

Not sure there's much to do in Albany itself... but it's a good travel crossroads...

There's some info about western NY in this recent trip report:
http://www.fodors.com/community/united-states/chautauqua-week.cfm

And a recent post about the Hudson Valley:
http://www.fodors.com/community/united-states/beginning-to-think-about-hudson-valley-drive-need-to-know-some-basics.cfm

I see ggreen has suggested an alternate route...among other things surely could include Niagra Falls always worth another visit. Yes, Cooperstown worthwhile and as mentioned above my report on Chautauqua week does mention some other possibilities crossing New York state. Of course Tanglewood in Mass.
Bill in Boston

As for the Detroit part of your trip, there are lots of things in the area. The only drawback is that you will need to drive. The Henry Ford is a large indoor/outdoor museum complex in Dearborn, about 20-mins west of downtown Detroit. It has Thomas Edison's Laboratory, Stephen Foster's House, the Wright Brother's House and Cycle Shop and several other historic buildings. The indoor museum has decorative arts, machinery and a top-notch transportation collection that includes all the presidential limos and the bus on which Rosa Parks was arrested. You can easily spend two days there if you visit both parts. Check www.thehenryford.org for hours and admission.

The Detroit Institute of Arts has a highly-regarded collection and is well-known for its murals by Diego Rivera. Check www.dia.org.

You could tour one of the auto baron's mansions. Meadowbrook Hall is about 45-minutes north of the city on the campus of Oakland Univ. The 103-room house was built by the widow of John Dodge and her second husband. The Edsel and Eleanor Ford House overlooking Lake St. Clair also offers regular tours.

The Cranbrook Educational Community is in Bloomfield Hills and houses an art museum, science museum, church, schools and the home of founders George and Ellen Booth. Many buildings were designed by Eliel Saarinen and Albert Kahn and there are numerous works on the grounds by Carl Milles and Marshall Fredericks. Check www.cranbrook.edu.

You are all so helpful and I do appreciate your taking the time to respond. Question re: Detroit .. I would be on my own much of the three days there with husband in meetings. Should that be of a safety concern to a slightly more than middle-aged female?

The suburbs and tourist areas of the city are fine. Always use common sense, but the areas of the city that are dangerous are places you wouldn't want to go anyway (unless you were looking to purchase things that are frowned-upon by the authorities).