I freuqent hold informal meetings in/around hotel lobbies. I have not found this discouraged anywhere, although "design" hotels with loud music or disco lights make it more difficult and thus I look to stay somewhere else. Any decent hotel 3* or above should be able to accomodate this for guests and their visitors. At hotels where the lobby doesn't have space- the restaurant should be able to accomodate with an order of a coffee/tea/water for each person at the table (of course not for large groups- however for 3 or 4 people this should be absolutely fine).