You will need passports to get back into the US from Canada. A driver's license or a birth certificate will no longer suffice. Also, be sure you are not carrying any thing prohibited when entering Canada, they have very little sense of humor in this matter. But be sure to stop at the Duty Free Store.
Entering the US from Canada in Detroit is always a PITA, but there is little you can do but answer the questions and smile.
Believe everything they say about the Henry Ford Museum and Greenfield Village. Set up the time to do it right (at least two days) if you are not planning to come this way again.
If you are going to cross the Welland Canal, go to
http://www.marinetraffic.com and point it at the Welland (just east of the Niagara River) and set up to see a ship or two lock though. The lock just south of the 405 has a visitor center, but there is usually someplace you can park to watch just about any lock.
Matt