A bunch of replies but still no perfect resolution. You should arrange with her in advance so there are no misunderstandings.
Room:
You reserve, you register, you pay = outcall (and you know the actual costs)
She reserves, she registers, she pays = incall (doesn't sound likely for this situation)
She reserves, she registers, she pays, you reimburse her for the room in cash
mrfisher reserves, Debbienoonergirl registers, perfecstorm pays - Wait a second. We're here to help but we're not THAT helpful!
You / She ... work it out.
If you register, YOU are the last to leave and check out. The room is in YOUR name and you don't want it trashed after you've left but before checkout.
If she registers, she can stay and do what she wants (more clients?). The room is in HER name.
Cost:
You're probably thinking more about the meeting itself, but you can also look for room rates on line (Priceline, etc.). That's whether you OR she is going to register/pay.
This is a trust issue, but if she agrees to reserve, register and pay and that you will reimburse her for the room, try to find out the actual cost of the room. Nothing like paying $450 for a room that was pricelined for $80! If she says the basic room cost is X, don't forget to add something extra for the final bill: hotel tax, tourist tax, laundry tax, toilet paper tax, ...
Charge 'em for the lice, extra for the mice
Two percent for looking in the mirror twice
Here a little slice, there a little cut
Three percent for sleeping with the window shut
When it comes to fixing prices
There are a lot of tricks I knows
How it all increases, all them bits and pieces
Jesus! It's amazing how it grows