dandbcat

Great tour, if you get there early enough to get tickets. The visitors center is no longer in a trailer by the Conoco, but rather in a new facility just north of I-90, off exit 131.
There are 3 locations associated with this historical "attraction". The first is the visitor center, mentioned above. Next, is the Delta-01 launch control facility where the guided tour is actually given. That facility is located off of I-90 exit 127. After that, or if you don't get a chance to score tour tickets, you could still go to the Delta-09 missile silo location for a self guided, or cell phone guided tour off of I-90 exit 116. It's pretty cool seeing an actual missile in its silo if your into that sort of thing. The multi-ton concrete and steel cover is partially pulled back and the silo is covered by glass.
Like everyone else, I recommend getting there early to obtain tickets. We wanted to do all three locations without delay so we were the first ones there at 7am. The next group was in the parking lot at about 7:20. We got our tickets when they opened at 8:00 am and the first tour was at 8:30 at the Delta-01 location. Since our guide was actually stationed in the launch control facility when it was active, we got thorough, first hand information and anecdotes making this one of the best stops on our trip. Though our kids were really tired from getting up that early, even they felt it was well worth it.