I am also a generous tipper for restaurant service because I have been a waitress myself. 20% for good service is my comfort zone. But I have gone above that for excellent service. I also like slipping some cash to staff that are not the server or bartender. After my sister's memorial service, I made sure to pass out some 20s to the folks who had set up and then were breaking down the tables, etc.
The one thing I refuse to do, however, is tip 15-25% on an expensive bottle of wine in a restaurant. Wine that is likely already marked up 50% or more. The server pops a cork the same way on a $20 bottle as they do on a $200 bottle. Unless there is a wax top, in which case, I'll add a bit more. So for fancy dinners out - rare for us - we take off the cost of the wine, calculate the tip on the remainder of the bill, then add in an extra $10 (or whatever their corkage fee is) to pop the cork.