I believe the concept of "double the tax" is a NYC thing since its 8.125% (or so).
There is a ton of debate about tipping on a $300 bottle of wine, as compared to a $75 bottle....is the service any different to warrant tipping on difference? Obviously from the server's point of view, s/he would wish the tip to be based on the total check, but from the diner's frame of reference, the tip is based on service, so does it take any more effort to uncork and pour the $300 bottle?

I was a tipped employee during college, so I know how it feels to be stiffed.

Finally, last week I experienced a first....an autogratuity of 20% for a party of 8 or more.....up to now, this topped out at 18%.