What's the ettiquette for a group of friends taking up a few bar tables but half the people don't drink? The other half buy a drink or split a drink w/their girlfriend [Right after coming from dinner to chat and play cards]
It's fine for the most part. Don't pull it on a weekend night. Have the courtesy to depart if you see too many groups waiting on tables.
If you become a problem, a manager will politely rush you, and as a last resort ask you to settle up and leave.
Get together dinners on a weekend night and then leave for the bar to hang out more when the restaurant closes around 10pm.
Maybe 3-4 drinks are bought for 10 people. Place is near capacity. Just hangout for an hour or two.
If they are not over capacity, and can still seat paying customers, the only person you are pissing off is your server. Tip them well, and it's not a problem.
If there are customers looking to sit and order food, you are costing them money, and inconveniencing the waiting customers. That's a dick move. You wouldn't want to wait, so don't make someone else wait.