I have found that it varies from hotel to hotel, so locations of buffets that you want to go to is important. For the Venetian, there is no buffet, but you need a Gold players card or better to bypass the cafe line (before we became Gold, my host would often just give me a pass). Mandalay Bay (not my host, just the players club desk) wouldn't give me a line pass even as a guest (TheHotel, not MB) playing 8-10 hours daily of quarter/dollar slots, plus a few hours of $25/hand table poker/BJ (lets just say I was losing 4 digits a day lol). I should have asked the pit boss while playing cards, but it didn't occur to me then. I can't remember what the deal was at Paris, quite honestly, but I think Platinum/Diamond only. My host at Luxor used to give me line passes just for asking, but I haven't been there in a few years.

Where are you staying/playing/eating?

Robin