Visiting Vegas next week and am not sure what to expect as far as upselling once the provider arrives at my room.  How much upsell is typical for FS?  I have only done flat rate services in other cities but can't seem to find any of those advertised in Vegas.  How do you tactfully get that info from a provider before you give her the initial fee, to avoid a bad situation if you can't come to terms?  Thanks

The simple solution to your dilemma is to not venture away from TER now that you are here. Do some research here, stick to those who are well-reviewed, make some initial contacts and you will not have to worry about all that other stuff you describe by the time you are here.

I sent you a message.

Upsell is not the norm and something you should not expect.
Check out the las vegas ad board there are many ladies who advertise there the rates are a flat fee.
I know many people think when coming to vegas that they will automatically get an upsell that is not true if one does his research first.If you go with a bait and switch agency expect to get an upsell and not the lady in the picture.If you go with a well-reviewed provider you get the lady in the pics and no upsell sounds like a simple answer to me.
If you do not already I would suggest purchasing VIP membership here to read the reviews and the profiles of the providers you are interested in.Also,checking out their website for rate info as well is helpful.
Good luck to you and enjoy vegas

TER has a top 100 list, and none of the providers would upsell to hurt their great reputation.