Upper Michigan South then to New Hampshire

Just Lee..dont quite understand how you are coming into MI on I-75. Are u entering from the UP or from the Chicago area? EEK! 5

Having traveled between Buffalo and Detroit numerous times in my life, I can tell you that:
1.) Sarnia is probably going to be quicker
2.) Crossing Ontario, while boring at times, is pretty flat, unlike what you'd be challenged with by going through Ohio and Pennsylvania.
3.) Lewiston/Queenston is faster than the Fort Erie/Buffalo crossing. But, if you're going to visit Niagara Falls, stay on the US side and walk back over to Ontario. NF, Canada can be Motor Coach Hell.
4.) There are few campgrounds within 25 miles of Niagara Falls / Buffalo, so plan well in advance. (This is one of my largest peeves with NYS Parks.)
5.) Some roads in NY, VT, NH, and MA are noted to be "scenic", but use your better judgment. Changes in elevation might not be large, but some of the grades can be overwhelming.

We took I69 through Sarnia, ON and Toronto on our way to NY Adirondacks on our way to VT, NH, & ME a couple of years ago. We came home via I80. Definitely go through Canada. Fuel may be more costly (not sure of US vs. Canadian dollar), but the ride is much less hectic. Toronto was busy (and we hit near post-work time rush), but we moved along quite well.

Just,

It sounds like you have a plan.
Crossing into Canada at Detroit isn't bad (never has been), but don't come back that way. Do not plan to be carrying any fresh food when entering the US.

We go into CA a lot as DW has family there. We also go east from SE MI pretty often - again for family.

If you choose to stay in the US, it is simple to cross OH and NY for zero tolls. Just ask. I am here about every other day and a private message will get noticed.

Matt

If you cross at Sault Ste Marie, Killarney Provincial Park is a good overnight stop just a little south of the SOO. It is one of the nicest and most scenic parks in eastern Canada and is a little bit off the Trans Canada. It is even worth an extra day to rent a canoe and go into the back country on a day trip.

Thanks I was actually thinking about head north on 75 into Canada that way and then across. At this point in our trip the gas prices won't matter.
But then we would miss most of Michigan. Hmmmm

Thanks for the web sites also

I-69 is a good route. I like crossing at Port Huron/Sarnia better than Detroit. Are you going to cross back in at the Falls/Buffalo area, or continue across 401 into Quebec?

If you want a much more scenic route, though higher gas prices, once you hit 75 go north and cross into Ontario at the Soo, and then take the Trans Canada Hwy 17 across. At least you would avoid Toronto traffic if your planning on the Quebec route.

There really isn't much to see, scenic wise, between mid Michigan until the other side of Toronto, but for a quicker route it works.

To enter Canada:
http://www.cbsa.gc.ca/menu-eng.html

Ro re-enter US:
http://www.cbp.gov/travel/us-citizens

Review list of items you cannot bring into US. Review medication rules. When we re-entered the US, we were asked where we had been, the purpose of our entry into the US, where we were going, did we have any fruits and vegetables, meat, cigarettes or liquor. Of course guns. They did search some boats in front of us. It took us longer to come back into the US than get into Canada.