Dumb question, maybe, but here goes:

I've twice seen a provider I'd like to see again soon (a gem), but much time has passed between each meeting, so there's probably no real familiarity.

Her Eros ad states no price, and never has to my knowledge. Past TER review information said $$$. Current TER review information says $$.

Both our meetings ended with a donation envelope laid on the table ($$$) and nothing said about it.

So, if that friendly protocol were to be followed again, what should be inside? $$$? or $$?

I want to be generous and appreciative, but hey, $ is $. I could live with either figure, I guess - or would be more than happy to split the difference - but who wants to lay out more than is required?

Should a guy just ask?

Question back to you, What did you leave her on your 2 previous meetings?

If you are uncertain, ask the lady as to what she would like for you to leave her. If she is a top notch lady she will give you a fair price and not bend you over.

be prepared to tip the extra $.

She may be having a really off day.  Then you'll be happy you saved it.  If she's outstanding (or if there is a negotiation of some kind) you got some extra scratch.  Think of the good will you'll buy for a 100 tip.

She just may remember you the next time.

Don't put a lot of value on TER review info.  If she is a top-notch provider $$$ is more probably the expectations for an hour.  $$ might be the case if its for 1/2 hr, but then she could be an exception.

Thanks for the advice. Bottom line, it seems, reasonable people WILL work things out.