Documentation wise, you'll need passports, plus possibly any vet papers for the pets to get into Canada. Coming back you might also need proof of ownership to prove you didn't just pick up the RV Canuck side.
Aside from that, if you do carry, your best bet is to find some kind of local storage and not even bring them. Pretty much you won't be allowed to carry anyways, so it's not like you're missing out on having them. If you have no other choice but to bring them with you then absolutely make sure you declare them. In the CSBA's eyes, failure to declare = smuggling = serious offence. As long as you declare, it's not so bad. They'll most likely either be confiscated, or you'll just be turned back, depending on the officer. Of course, if you don't carry, no worries.
Following that, there's not much you have to worry about regarding food stuffs, etc... As pointed out above, inspection.gc.ca has the list of what's allowed and not, but generally they're not as restrictive as the US. Coming back, avoid bringing back anything fresh (fruit, vegs, etc...) and in most cases you'll be fine. Unfortunately, the US side as too many hands in the pot to try to determine everything that is or isn't allowed. (CHP, USDA, FDA, CDC, etc...) Some aren't even things you'd normally think about. For instance, Minute Rice can't be brought over. (That reminds me, I need to remember to remove the rice before our trip this weekend.)
Alcohol and smokes are allowed for 'reasonable personal consumption'. For us Canadians returning to Canada, this equates to 1 40 oz'r or a case of beer or 2 bottles of wine and at most a carton of cigarettes. While that's the official rule, I believe the American visitors are often granted more leeway. I wouldn't try to push it though. They're gonna be curious if you're trying to claim you're going to drink 20 cases of beer over a 2 day weekend; however, a modestly stocked bar of 4-5 bottles that are open and at various stages of use could possibly be OK.
Also, you said you're coming from Michigan. Both Michigan and southern Ontario are under a quarantine on the transportation of firewood due to the emerald ash borer and some other insect. So don't bring firewood across.
Most of what you need to know, aside from what's on inspection.gc.ca can be found on the CBSA's website:
Travellers - Visitors to Canada