I'll start with the Midwest (St. Louis) Regional, since it's in the upper left of the bracket and as such, it's logically the first place people look.
This regional seems to be the only one where people aren't griping about some kind of seeding issue. There's the occasional "Winthrop is way too high" whining, but that's pretty much it. As such, this seems to be the most boring of the regionals in terms of upset potential, so it's probably good that I'm getting it out of the way first.
In the first round, I don't really have my finger on any upset possibilities. Some people seem to think Notre Dame is ripe for a letdown against Winthrop, but I really don't think a team that took Georgetown down to the wire in the Big East semis is going to lose to a team that played absolutely nobody all year long. Looking at Winthrop's early season schedule, they played some teams that quite frankly I'm pretty sure don't actually exist. North Greenville? Presbyterian? Limestone? How do these games even count? Winthrop then proceeded to go 1-4 against other teams that are in the tournament, their only win at Old Dominion (which I'm not sold on, either, as I'll explain in a second).
The other sexy first-round upset pick here is Old Dominion over Butler. Normally Bill Simmons is a complete idiot, but in his NCAA Tournament preview, he actually said something that made a little bit of sense:
While Bill Simmons doesn't actually know anything about college basketball, I have to agree with him in this case. As beastly as the CAA is, it's really not. And Old Dominion wasn't even the best team in the CAA. I mean, it's obviously a distinct possibility that ODU advances, but I'm not gonna get caught up in the OMG 12/5 frenzy.
This happens every March: There's an obvious 12-over-5 upset pick (in this case, Old Dominion over Butler) that sucks everybody in and/or freaks Vegas out to the point that they practically make the game a pick 'em (in this case, Butler by 1.5) ... and then the No. 5 team ends up winning and we all feel dumb.
One thing the NCAA selection committee seems to always do a really good job of is picking 8/9 games. They usually are real toss-ups, and we've had some pretty epic contests come out of the 8/9 games in recent years. This year is no exception, and the only technical upset I'm calling in the first round in the St. Louis Regional is #9 Purdue over #8 Arizona (although according to this thread at Pitt Blather, the 9 seed actually wins more of these games than the 8 seed). I can't even pinpoint a real reason here. It's just something I feel. Both teams have been extremely inconsistent all year long, and I guess I'm just making this pick based on the fact that I like the way Purdue hung with Ohio State for most of their Big Ten semifinal game. It doesn't really matter that much, since the winner will just get humped into submission by Al Horford in the second round.
Speaking of the second round, I've got all the favorites progressing to set up a Sweet 16 with all four of the top seeds. Boring, I told you. I think Notre Dame is most capable of pulling an upset, over Oregon, although I think the game swings in Oregon's favor in large part due to the fact that the game would be in Spokane, Washington, which is kind of far from South Bend but not all that far from Eugene. I'm not sold on Maryland at this point, either, but the Terps would be playing Butler, which might not even get past ODU. Either way, the last sentence of the above paragraph applies here, too.
Wisconsin was one of my early-season favorites. They looked awesome early on, but they've slowed down quite a bit recently, and didn't even put up a fight in the Big Ten Championship Game. I went from talking about them as a championship contender to knocking them out in the Sweet 16. I think even Notre Dame, if it gets past Oregon, could beat the Badgers at this point. Hell, it wouldn't even be out of the question to see UNLV upset Wisconsin, although the game being played in Chicago will help Alando Tucker and company avoid that.
That all sets up a Florida/Oregon regional final, and I'm taking Oregon, for a few reasons. First of all, occasionally I'll let a personal bias pick sneak in, and this is one of those instances. I make no secret of the fact that I have no love lost for the SEC, and on top of that, I hate it when teams repeat in March Madness. One of the more fun aspect about college sports (from the perspective of someone who isn't attached to a single team) is how volatile they are, with the turnovers caused each year by graduation and going pro. Florida winning again would be terrible. But I really do think the Ducks are capable of pulling this off. They've had their poor spots this season, but they're really as a complete team as there is in this regional.
Here is my final bracket prediction for the St. Louis Regional: