Bobs is best visited on off hours, this is true (1pm on a tuesday, go for it. 3pm on a saturday, eh not so much). Last time I went there were only two other groups in there, a father/son with 22 pistol, and a group of 4 college senior-ish age who rented a pistol caliber carbine (don't remember which one). Other notable, the range is "heated" in the loosest sense of the word - i don't put much stock in the pellet stove they have in there.
Granite state, is fully heated/cooled, electronic target system (punch in your desired distance), and they''l let you shoot up to .308. Also, they're $20 till your done, not $20/hr. If I was closer I'd probably go there quite a bit more (I'm basically next door to bobs and i've still been to GSIR more often).
Joe, the guy who owns On Target Firearms in Dracut was in the process of building a range down the road from his shop when I swung in over the summer; was supposed to be done late november. Haven't taken the time to go see if it got finished yet.