Often when I am closing a waiter will come up and ask me to watch a table for them that has paid and are camping out. The waiter just wants to go home so I say sure I will watch it for you. In our restaurant we are allowed to pass off a table to someone else if they have settled their bill especially when the waiter has been waiting for them to leave for a long time. As long as the waiter taking over the watching has been introduced to them. Usually this is enough to get them out of here but in case they decide to hang around further I try these methods.
Last week I totally cleared everything off their table except their water glasses without saying a word which prompted them to remark they will be leaving shortly.
Another method I use is politely walk by them and fill up the salt and pepper shakers in that area and take theirs’ as well to fill it up without saying anything. This action implies I am doing my closing duties.
One action I took last night was to walk by a table quickly making eye contact with the guest and putting on a faint smile indicating it is nice of you to come but I would really like you to leave now. The two ladies got up shortly afterwards.
The best story I have though is when I worked in this restaurant and I was the last one there and did all my closing duties. I was responsible for closing and setting the alarm. If a table was still there I would put my jacket on and jingle my car keys and walk over to the table and in a happy merry voice state we are closing in a few minutes. The appearance of me in a coat pretty much gave that impression.
One thing I have noticed though is when I have taken care of other tables the server has left a lot of used items on the table. For instance the other day there were some bread baskets and butter ramekins still on the table when they should have been long gone. Some servers when they leave stuff that should be taken away on the table might give the guests the feeling of sitting at home at their kitchen table where conversations can go on for hours on end. You know when you sit at home after dinner not much of a fuss is made about properly clearing the dinner table.
My suggestions maybe are not new to anyone but worth remembering. The last point is important though and that is rid the table of everything you possibly can. Even the coffee cups that have long since been drinken out of. Leave the water glasses with some water still in them but I would take the empty ones away.
Your goal is to get them out of there.