Google Analytics tells me we have reached 1.5 million visits a month - which is a level we've never hit before.

Total "Visits" is a little different from total "unique visits" which are just the total number of unique IP addresses for the month. I think a single visitor can have a few visits- based on an arbitrary time limit. So if you access at 9AM and then again at 2 PM - that's counted as two visits. Total number of unique visitors is now 1,195,000. Total number of pageviews is 3,117,558.