A coaster is only effective if your dinner guests are willing to use them. Once you've left the room to check on dinner, it's all but guaranteed there will be glasses, cans, and bottles placed directly onto every piece of furniture you own. Unless, of course, those coasters were stuck to the bottom of every drink.
Even the laziest of visitors will be happy to use these Grab & Go coasters from Umbra, since they require absolutely no additional effort on the part of the drinker. You can even attach them to the bottoms of drinks before they're served, meaning that at no point is there the risk of them marring your wood furniture.