You should go to Murphy Hanrahan. It's a bit on the south side of things, Twin Cities-wise, but if you like fast, swoopy, flowy singletrack, you will be hard pressed to find anything better in the Mid West. Great trails and yes, there is a trail map at the trail head and one other in the system that I saw when I was there a couple of weeks ago.
Lebanon Hills is more technical, with log piles, stones, and a few skinnies and stunts. Very fun though and I like riding there alot too. I do believe there is a map at the trail head, but it is laid out so that all loops come to a "meeting place" in the middle. So, it's hard to get lost there.
I haven't been to Theo Wirth yet, but it's supposed to be very tight, flat and fun. Very single speed friendly from what I've heard.
Then there are the "river trails" down along the Minnesota River that are pretty flat, and going faster makes them funner. I haven't ridden these yet either, but I know several folks that say the river trails have their certain charms.
Have fun! The Twin Cities are a great cycling place, full of great stuff for bike freaks.