I find that my excitment level is a bit higher for MPA's that I'm seeing for the first time as opposed to repeats. The idea of not knowing what to expect is part of the fun in this hobby. That's not to say that I'm never excited in seeing my regulars ... I am, because they usually bring something new to the table on every visit.
With the first-time MPA, she may not know what pushes your buttons, so some instructions may be necessary, especially if the MPA is new. But, it's great when she tries something new and you say to yourself, "I have to try that with my regular because it could be on a whole new level". I like to take things that I experienced in one session and apply it with the regulars because it somehow keeps things fresh.
But the most important thing is the comfort factor when comparing a regular to a first-timer. With someone new, when she enters the room initially, its right down to business usually. She will make some small chit-chat and ask what option you would like. That's understandable, but with regulars, I find that those extra moments of cuddling and a great conversation at the beginning just make things better. The best thing: you don't have to tell her what to do ... she already knows.