New glarus, really anything from them they're all good Alesmith speedway stout, my favorite stout. Anything else check seekabrew.com Also if you're downtown check out downers, really liked that place
Depends on what you like. Do yourself the favor of checking out Black Husky, look at O'so for sours, the thumbprint series from New Glarus is solid, and see if they have anything special from Tyranena.
I agree with everything mentioned, especially New Glarus. Look for Central Waters, Lakefront, ale asylum and Fantasy Factory from Karben4. There's a few more I can think of, but that's a pretty good list. Incidentally, it was a high of four degrees today in Madison. You might want to wait till June. Enjoy your trip.
If you have time you should check out Milwaukee Brewing Company. $10 gets you a pint glass and pretty much all the beer you can drink. they give tokens for high ABV beers but if you make it through the tour they give you more! Its a fun place to hang out for a bit, very laid back atmosphere.
Lakefront Brewery tour is a must. I have done this twice, and is well worth the price of admission. Tour is about an hour long. Discount Liquor will overwhelm initially, if you have not been there before. Great selection. Make sure you go up and down the aisle at least 2-3 times. I was amazed how I missed a few beers the first pass. New Glarus is must and is set up in the back of the store.
Pseudo Sue is all over town this week. Discount may have some, otherwise Ray's Liquor and various Sendik's stores around town for sure. Probably a bunch of other places as well.
Seconded on the Lakefront tour if you have time. One of the best brewery tours out there. Done it a few times, and would do it again in a heartbeat.
They had quite a few cases of Sue near the back when I stopped there this evening. One four pack limit. I believe ZD is sold out but they did have other fff six packs and bombers.