anything from an overnight to a "I'm willing to be your kept woman sex slave". Kind of leaves a lot of room for suggestions doesn't it?

Possibly she means someone who sees her on some sort of regular schedule.  I had a provider offer that to me and the way it worked was I would see her on the first Sat. of the month and it was at a pretty good discount.  Unfortunately, my schedule at the time did not allow me to make that committment.
Arnold