If you dine out, in a sit-down restaurant, where someone actually brings food to your table, you should leave a reasonable tip.
I’m generally on the side of 15% as a base, though what I do in practice is double the sales tax. (Local sales tax around Austin is generally 8.25%, so that’s actually 16.5%.) I will tip 20% or 25% if I have a good reason to. I’m not as bothered by an 18% mandatory gratuity on large parties as I used to be; if the definition of a large party meets mine (five people is not large; seven+ is) and if they go above and beyond in some way (splitting the ticket six or seven ways for a party of seven, to me, justifies at least 18%).
In any case, I strongly recommend against a 200%+ tip, especially if you’re on an expense account.
Because if you’re on an expense account and turn in a receipt that shows you tipped the waitress at Hooter’s $24.52 for a mushroom cheeseburger that cost $7.48, somebody in the accounting department is going to ask questions. And eventually they’re going to find out that you tipped the waitress $24.52 to cover your bar tab, since your city expense account doesn’t cover alcohol.
(The heck of it is, I think the city policy is unreasonable. It doesn’t bother me that much for a couple of off-duty cops dining out of town to have a beer or two with their meals, and have the city pay for it. As long as they don’t get messed up and embarrass the city, say, by having the waitress pose with their patrol rifle, I don’t get hot and bothered by adults having a beer. But if they knew city policy was otherwise, and they lied about it because they were too cheap to pay their own bar tab, yeah, fire their butts.)
(If you’re not on an expense account, the above doesn’t apply to you. Feel free to tip the waitress 200%. Or 300%. Or 500%. But keep in mind; she’s not going to sleep with you, no matter how much you tip her.)