We were visiting Detroit recently, and since we were so close to the Canadian border, we decided to hop over to Windsor, Ontario for dinner. Getting across the border into Canada is very easy. You can take either the Ambassador Bridge or the tunnel into Canada. I would recommend taking the bridge as the view is spectacular. Before you get on the bridge, the United States charges you a $5 toll, which I found a little outrageous. (They also charge you AGAIN to come back into the United States. Canada doesn't charge at all!)
Once you cross, you have to go through Canadian customs, which is relatively painless. Once you are through, you enter right into Windsor. We turned off cell service on our phones just incase we were charged for roaming, so we had to just depend on our own navigation to get us to the downtown/restaurant area. Once we found it, there were plenty of little restaurants in the cute downtown area to choose from. We ate at Foundry Pub, which is a two story restaurant with lots of outdoor seating.
After we ate, we went to Caesars's Hotel and Casino for a little bit of gambling. After we lost some money, we traveled back into the United States again via the Ambassador Bridge. Getting back into the USA was much more challenging than getting into Canada. The lines were longer and the inspection seemed more thorough. Plan to spend a good amount of time at the border.