I went to vistaprint and printed out the oversize postcards for my menus. I too am having a buffet and alot of people think I have lost my mind, my tables will be bare without plates or chargers and I thought the menus would look really nice tucked away into the napkins.
And also, instead of opening the flood gates to the buffet, I am having my DJ (MC) dismiss tables one at a time, so that will give the others sitting at the table, time to look at what being offered.
ETA: I also had read awhile back about people being thankful there were menu cards at the table for different reasons. For one, say you are a vegetarian. And you fill your plate up with a salad, and then you find out they offered a meatless entree. Or you see that there will be chicken down the line, rather than filling you plate up with pork.
Its more of a courtesy than anything. And nobody is going to think it is "rude".