I don't understand this whole "the club has to invite you" deal. Unless you've played there before with great results, there is no booking agent in any club around this country who contacts lesser known bands to get them in their club. SymphonyX, as awesome as they are, doesn't have a following to warrant this type of recruitment. Therefore, the only way these guys are going to get into a club who doesn't know them is for their label/management to call these clubs and sell the band to them. All they have to do is show them the returns from previous tour dates and the club owners will let them play if they think it's worthwhile. Once they play there they might get invited back, but there is no way the clubs will be going out of their way to get SyX to play there.
Therefore, don't waste your time going to the club unless you have a large number of people backing you up who will attend the show. Then, maybe, you could convince the booking agent to contact SyX's management about having them come down there, but it's doubtful.