...I always think of the whole damn thing as a "tip".
So my only thought is "What's the expected tip amount and do I give more?".
Getting back to the OP's original comparative, "Yeah, like a restaurant..."
18% is the norm (15% in some places), and better places are 20%... So you know you're going to pay it. (that's "rate", let's say). If you don't pay it - you're a dick (or, possibly a foreigner... some of them NEVER tip, ask servers)
Now, do you "over tip"?
Hmmm...*Exceptional service? *Unexpected kindness and attention? (Yup, and yup... I can see those. You're tipping as a "Thank you" and recognition).
**Although, I'll explain - the things that happened at your last restaurant that you felt were so "special"... they do all the time. Better restaurants are not YMMV... they are BBBJ every night.
Repeat service? (Yes, I tip more at restaurants I frequent so they understand the caliber of service should continue - and I do get preferential services - as said by others; primarily "booking preferences". Trust me, I can get into most DFW places with a phone call - even on a holiday).
But - if you're not going to be a frequently returning customer, or it's your first time... over-tipping at the end does you no good (accept maybe - warm and fuzzies).
You know what does you MORE good... Pre-tipping.!
Pre-tipping the Maître D, or the chef can get you a tremendous "first time".
I've tried this concept with some providers, and it changes the dynamic of the first encounter in a very positive way. Suddenly you're seen as someone who is more genuine. Will it lead to higher rates and GPS? I really don't think so - because it's the "Unexpected" versus the "Expected". Usually (time is money, right?) it means the "clock isn't so important anymore" or the "time to enjoy the wine and conversation" is acceptable. But again, it's an individual thing... and while I'd like to say "It works", all I can say is (occasionally) it works for me.
As for "Upselling"?
I never re-open a card or envelope. High or low, over-priced, underpriced, a bargain or a flop... the agreed upon amount (without hassle) is there. Asking me to dip into my pocket, during a session? (gauche, unprofessional... and personally, it would guarantee a "no" review).
