Hi TheNightKing,
Each Testing Facility can only accommodate a certain amount of Test Takers each day (and it's possible that the Facilities that you're considering run more than just the GMAT). If all of the available 'spots' are filled right now, then it's certainly possible that someone might choose to reschedule his/her Test Date in the future - at which point that spot would open up.
Considering the 'busy' time of year (since many applicants are trying to make application deadlines), if a spot does open up, it likely won't stay open for long - there are almost certainly more people besides you who would take that spot if it were available. As such, you might want to check the website regularly (perhaps even daily) to see if anything becomes available. You don't seem particularly interested in that Monday, but Monday morning Test Times tend to be great for most GMATers. Since most people work Monday - Friday, a Monday morning Exam would give you the prior weekend off (to get in some extra rest and light review), so that you could go into the Exam calm, clear-headed and ready to work.
GMAT assassins aren't born, they're made,
Rich