I recently visited Detroit but stayed at a Windsor hotel. It was the only hotel with reward stay availability for my entire stay.
The drive from Windsor to Detroit was pretty short, sort of like from New Jersey to New York City. The only slow part is getting past the US and Canadian border agent. I ended up crossing over only once a day, except for one day when I crossed back and forth 4 times. That apparently me got me noticed because they made me go to secondary. Since I had nothing to hide, I wasn't worried. I just explained the reason for so many crossings that day and I was allowed to go on my way. However, something the CBP agent said stuck in my mind. Exact quote:
"you are only allowed to cross the border twice every 24 hours" 
Is there really a law or regulation that says that?