We go here often..sometimes weekly in the summer. You can either drive up the mountain road or hike. It's not too difficult of a a hike. If you can hiking is the best way to see the mountain. If you are lucky you may see some widlife here. Some of the things we have seen are deer, eagles, turkeys, a porcupine, a fox, and red efts. (Red Efts are small red/orange salamanders. Here is a link to a site with more information on them:
http://www.exploringnature.org/db/detail.php?dbID=43&detID=725. They are fascinating. My kids love looking for them. Look after a rainstorm and you are sure to see one. ) Plan on a morning or afternoon to complete the hike and explore. Seasoned hikers can do it in less time, if you just want to go for the hike. There are lots of trails, but the shortest and most popular is directly behind the ranger/ visitor station. You can also walk on the road, but watch for cars as the roads have lots of turns. If you do drive up be sure to get back down before sunset. I believe there is also a $2 per car fee to drive up. The gates are locked at dusk. Usually during the summer a ranger will walk around the top and let people know they need to leave. The road is opened seasonally , so check the website for opening and closing dates. Also check out the center of Princeton ( a little further up the road). It is a quaint little new england town with lots of historic buildings on the common.
Take the auto road to the highest point in Massachusetts east of the Berkshires, with spectacular views of Boston, the Western Massachusetts Berkshires, the New Hampshire mountains, hawk migrations, and the autumn foliage spectacle. Within the 3,000-acre reservation there are 17 miles of hiking trails used in the winter for crosscountry skiing. WARNING: Hunting is allowed at various times during the year. Check with the mountain before you hike.