They let you go in the bullpen and clubhouse? Is this only because it isn't baseball season or will they do this during the season too?
This is the first tour I've heard of that lets you in those areas.
From the link that NOTLD posted:
Take the Nationals Park Ballpark Tour for a behind-the-scenes look at Nationals Park. Over the course of an hour and fifteen minutes, our entertaining and knowledgeable guides will provide an up-close and personal experience of the ballpark, regaling visitors and fans with baseball history and anecdotes, including visits to:
* The PNC Diamond Club, the Lexus Presidents Club and the Stars & Stripes Club
* A Luxury Suite
* The Press Box
* The Nationals Dugout
* The Nationals Clubhouse
The tour will encourage you to participate and include interactive portions:
* Touch a module of the spectacular five-story HD scoreboard
* Experience the Nationals indoor batting cages
* Throw a pitch in the Nationals Bullpen