As an ex-waiter in a number of great places in Miami, I agree 20-25% is a good tip which will be appreciated by your server. Especially in this day and age. Round it up a little if you intend to come back to that restaurant. You will be surprised how good the service will be next time you show up! Yes, Servers have good memories, and they tell each other who the good tippers are. Changing the subject slightly, does anyone have an opinion on whether to tip tow truck drivers when they are towing you under contract with AAA etc. I have wondered about that.
My first post on tipping (which I apparently overcomplicate given the other posts) became so long that I cut if short.
It's hard to be a server and there's a night and day difference between a good server and an indifferent one. It goes beyond whether they show up to refill water or a bread basket.
If I frequent the same restaurant and receive excellent service, I not only tip well, but I let the manager know that I received good service and I remember the server's name.
On return visits, I ask to be seated in that server's area and specifically state it's because of the quality of the server's service. I may not get the server - but I'm certain it's helpful to them. If I get another good server, then I'll mention both servers the next time I dine at the restaurant.
If I receive great service form a server who is a senior, a student, or single parent (yes, I chat with servers if the restaurant's not busy) - particularly if I'm a regular - I may tip an extra $20 on a small tab, particularly around the start of school, the end of the month, or a holiday.
If my server is handling a couple of tables of drunks, a family who can't control its children, or some demanding jerk, and still manages to give me good service, I over-tip and explain why.
If I'm with colleagues, clients, or friends, and one or more of them is a pain, and I am responsible for the tab, then I over-tip.
And, yes, I find I am called by name upon return visits even by servers and other employees I've never met. But that's not why I do it.
I sincerely do not believe that one size fits all when it comes to tipping.
Like it or not, we have a system where you pay for your service based on what you think it was worth. Truth be told, sometimes the service is wroth 5% of the tab, and sometimes 100% or more of the tab.