I have seen the restaurant business from a range of perspectives. I've owned one, managed several, bartended for some, written about lots, and been a regular and incidental customer at many. As I've noted in previous rants (see "Gridlock on Aisle Five"), I don't claim to be any sort of arbiter of social correctness per se, but some of the behavior I've witnessed by restaurant customers is appalling.
The straight-up fact that seems to have escaped many who venture out is that while restaurants provide a hospitality service, they are, in fact, businesses. So just because you made a 7 o'clock reservation doesn't mean you can chain yourself to the table for the night. On busy evenings at popular spots, about 90 minutes to two hours is likely what's been budgeted for your experience and that should be ample time to enjoy a leisurely meal before doing the polite thing and giving up the table to the customers who reserved it for 9. On a jam-packed Saturday night, when you can plainly see customers waiting for tables, if you've finished your drinks and/or your meal and your check has been sitting on the table, pay it and go. If you've been lingering over espresso for a half hour and a polite manager or server comes to your table and offers to buy you an after-dinner drink at the bar, accept it graciously and get up. I know you just spent a car payment on dinner, but that was your choice, and believe it or not, this is how this business -- the restaurant business -- pays the bills. The diners who follow you are just as important to the restaurant as you are.
Unless you're a designated driver, scoring a bar seat at a busy tavern does not give you the right to park there and linger over water for hours while bartenders trying to make the rent are forced to reach over you to serve paying customers. A bar is not a highway rest stop. It's someone's living. It's several people's living, from the owner to the bartender to the busboys and bar backs. If you're done dining and drinking and you know people are waiting to do the same, get up!
Moving on to gratuities. If you order six drinks and leave a $1 tip, put simply, you're cheap. A general rule of thumb on an order of one to three drinks is $1 per drink. Beyond three, use your judgment, but remember that bartenders and waiters generally make below minimum wage, with the understanding that they will make up the difference in gratuities. If you've been waiting for your table, and your bar tab can be transferred to your dinner check, you still need to tip the bartender for his or her service.
As for tipping on a dinner check, whether you're seated at a table or the bar, 15 percent is the absolute minimum you should leave if you're a respectable customer, and that tip should be calculated based on the entire amount of the check (I have never understood the theory of subtracting tax or liquor before calculating the tip -- it's not as if those tax and booze dollars are going into the waiter's pocket). Personally, unless the service is abysmal, which certainly can happen, I never, ever leave less than 20 percent. And by the way, if you happen to like a restaurant, those extra couple of bucks can go a long way to getting you faster and better service than the rude guy next to you who throws change on the bar after ordering four different martinis and three beers.
Finally, please don't yell "Yo!" or ever snap your fingers to get a bartender's attention. Who does that?? If the guy's "in the weeds," ie: slammed, the best thing you can do to expedite your drink order is to have your cash or credit card in hand (please don't wave it around like a flag) and know exactly what you want when it's your turn.
Bar "real estate" can be precious, and no one knows this fact better than I do. More often than not, I prefer to dine at the bar, so my boyfriend and I will hover at a respectable distance as we await available seats. The key here is personal space, and for God's sake, if you've already got your cocktail, let others slip in to place their orders. There's nothing worse than having to play a round of "Red Rover" just to get to the bar. And unless doing so will put you into a bus tray, if there's an extra seat on either side of you and two people come into the bar, move over. Be kind to your fellow bar fly. Share the wealth!