Kieran's Irish Pub is right downtown. Don't let the fact that it's on the ground floor of a big office building put you off. It's the best Irish bar in town. They have 2 rooms. The front bar is usually rowdy bar music, Black Velvet Band an' all. More traditional music is in the back room, the Titanic Lounge. When the weather's warm, as it may be by May 4, they move the traditional music outside to their large patio. It's a great venue.The other great venue in town is Cedar Cultural Center, easily reachable by bus. I see they've got Dougie Maclean on the 4th. I would advise buying your ticket in advance if you have your heart set on going to that. The Mayday festival they mention on the 5th might be in part sponsored by them, but it's not held at the theater. It's in a park some distance away.
Macalester College's Scottish Country Fair will be going on in St. Paul on the 4th. I see it says that "The Scottish Country Fair has been selected as one of the 'Top Annual Group Tour Festivals and Events' by the American Bus Association." I guess that means you can't miss it! Seriously, it's well worth the trip IF you have at least 2-3 daytime hours to spend there.
A Cinco de Mayo festival will be happening along Lake Street (near Bloomington Ave.) in Minneapolis AND on the "west side" of St. Paul, Sat-Sun. The one on Lake Street will be more accessible to you. A lot of Hispanic-owned businesses have sprung up in recent years along that part of Lake Street.
The Uptown area, at Lake St. & Hennepin Ave. has several things that will be of interest to you. There's Booksmart, a used book store, at 2919 Hennepin Ave. S, according to the phone book, but I think they recently moved a block or so south of that location. And there's another great recently opened used-book store nearby, whose name I don't remember, but I think it should be in the 3000 block of Hennepin, on the west side of the street. There's also a Borders Book Shop across the street at 3001 Hennepin Av S. In the same building as Borders, there's Famous Dave's Restaurant, which specializes in barbecue. In the evening they have live blues bands. Click the link for their schedule. There are lots of interesting shops for a couple of blocks in any direction from Hennepin & Lake.
City Pages, a free weekly tabloid, probably has the best schedule of entertainment events.
If I run across any more information, I will post it. Will you have Internet access while you're here?
I live in St. Paul. Feel free to ask, if you want more info. PM me if you want my home phone number.