They sometimes give you some type of new-member special for one day of office space on a trial basis. Otherwise, no specific access to these offices.

All the centers I've been to, showing the Regus card is sufficient since they swipe it. Never had to show the AC card.

I've been able to use wired internet access in what amounts to the breakrooms of these business centers. Usually free coffee/tea and water, but that's about it.

Luckily, the one near my place posts a calendar when they bring in free bagels and catered lunches