MPLS is a great city for viewing great art spaces. I would recommend checking out Le Meridian Chambers hotel downtown on Hennepin. There is some really great modern art in the lobby by artists like Damien Hirst. There is also another gallery attached to it next door that can be hit or miss.
The walker is fantastic. The Walker sculpture garden is also a great place to sit and people watch if the weather is nice. You will also have a birds eye view of the Basilica of St. Mary, which is the first basilica in the US.
The new Guthrie is pretty amazing too, definitely try to see a show there if you can get tickets. I would also pick up City Pages when you get in. They outline what to do for the week, wether it's movies, dance,concerts, plays, etc. It is usually pretty helpful for city visitors because of the wide range of suggestions.
Getting to the Frank Gehry designed Weisman art museum is really easy on public transportation, leaving from downtown.
The city also has bikes you can rent throughout the entire city, which is a great way to see things or go for a ride around the lakes, which most locals like to do in warmer weather. It's great eye candy to sit on the water and just people watch. (You while see racks of green bikes all over downtown for pick up or drop off). You will also notice city ambassadors walking around the city in the same bright green color, and they come in handy for directions and suggestions.
As long as you aren't coming to the city to party and have a "boystown" or "west Hollywood" experience, I think you will like it. The boys here are not too outwardly friendly, so be prepared to strike up the conversation if you want to get to know the locals. It used to frustrate me, but people are great once you start talking.
The shopping in the city is pretty average, especially if you are from Toronto... but we don't pay tax on clothing, which is great.
The newest place to eat downtown is Tom Pham's Wonderous Azian kitchen on Hennepin. He is sort of a well know restauranteur around town and might be worth checking out or stopping in to have a drink. (the local beer is Summit, btw.) I would also check out First Avenue nightclub if you are into Prince at all. It is were Purple Rain was filmed.
This is a city without a lot of pretense or showing off, but people are always telling me how surprised they are by how clean it is and all of the things going on around the city, especially in the warmer months.