I was going to post a similar question... then I found this thread. We're also planning a weekend in Milwaukee in early June. The Museum is a must... and we're looking for a few other things to fill our time there.
We'll be a small group. Just 3 or 4 bikes with 5 or 6 people.

 

I'm a little late on this thread, but better late than never. I have a few other recommendations that might be of interest. If you are in the Milwaukee area on a weekend, then a ride to Madison to the farmer's market is a lot of fun. It is a morning event, but since you will be riding west from Milwaukee, the sun won't be in your eyes. Lots of stuff to eat and then hit State Street for some a good lunch, drinks, and people watching. There are at least three ways (Hwy. 18, County rd. B, Hwy. 16 to hwy. 19) to get there and none of them are on I-94.

Wisconsin is loaded with good motorcycling roads. All of the county roads are good rides and are rarely straight and flat. The kind of meander from farm to farm and are all good surfaces thanks to the dairy industry. Riding the Kettle Moraine forest area is really nice and it is just half an hour from Milwaukee, if that is where you are staying. You could easily burn up a day with good riding out there. That area runs North and South starting down by Elkhorn and goes well North of West Bend. Once you get in that area, the best bet is to take any road that you see that you like. If you get lost, just stop at any one of the many watering holes where you see bikes parked and get directions (and meet some new friends). That's half the fun.

Here's a site for a bit more info. http://www.motorcycleroads.us/regions/wi_east.html

 

+1 on Kettle Moraine Area, another idea to avoid the Chicago mess is to run up to Muskegon Mi and take the Lake Express Ferry across to Milwaukee. Although pricey it's a nice way to avoid the Chicago traffic, we use it a few times a year when we visit friends in the Milwaukee area.

 

If you go through Chicago, be aware of the left side merge on ramps...they can scare the bejeezers out of you if your concentrating on the traffic and not realizing that traffic comes into your lane from blind spots on the left when you are already in the left lane. Most people fly into the traffic from the ramps since the traffic is usually faster than the other lanes. However, you'll love the idiot that comes flying, then slams the break when they just start the merge into your lane because they just caught you in their peripheral vision and they are now stopped 1/2 way into your lane.

We went to the HD museum during the 105th. We like collecting shot glasses from the dealers we visited, and spent 2 days hitting nearly 2 dozen dealers in the area. Lots of good riding away from the interstate up there, especially north of the big city.

Make sure to budget enough time to see the museum. If you like those places there's tons of signage to read throughout. We missed much of it, and we were there for 3 hours. Some people like the food at the on-site restaurant...we didn't. It way too expensive for the quality of the food. A buddy of ours was there a few months ago, and he said the same thing when he got back. I hear there are some high rated restaurants in the area though.