I live near Boston as you know since we've talked before. I've also been heavily involved with the professional gaming community, specifically that of Halo and Super Smash Brothers so as a result I've been to many LAN centers. There is only one major LAN center in Massachusetts and that is in Framingham although I hear they have a new location in Somerville. They were called Game Universe before but now their Game Underground. I would highly recommend seeing their setup before you start your own since its not far from you.
One of the best ways of getting a strong hardcore following with people that spend on games are tournaments as Yo_John said. The best tournament games that attract the most people are Halo 3, SSBB, Street Fighter 4, Star Craft, WoW (PvP), Gears of War, Tekken and Gran Turismo. Even having a DDR machine setup or Guitar Hero will get you many customers.
For the tournaments you should give the players store credit so you keep the money within your own store. For second place you should give free games and third place a t-shirt or whatever trinket you want.
Specifically for Halo I watched Game Universe go from having a messy tournament with only like 5 or 6 teams to a highly structured tournament using MLG rules with over 20 teams and each player paying 15 to 20 dollar entrance fee's.
I have to go out with my girlfriend right now but I'll be back later to brainstorm some ideas with you. I would be interested with helping you out in my free time too.
The definitive evidence that video games turn people into mass murderers
