The early weekend rounds (like the first saturday/sunday of main draw play) can sell out if the weather is really nice - but then i think they open up grounds passes which get you everywhere but the stadium (and I know for myself I BARELY went into the stadium in the 3 days I was there last year b/c there's so much to see and do on the outer courts and around the grounds :lol: ). But I think you can usually get night session tickets, it's the day that's the problem I *think*. The best bet, if you know when you're going, would be to buy in advance though - even if it's a day in advance. The problem seems to be in the morning, people line up for tickets for that day and that's when they sell out, at least this is what I've witnessed the past couple years.
I'll be there Friday-Monday, the 13th-17th, would be glad to say hello

I think there will be a few other MTFers there throughout the tourney as well, maybe they'll post here!