I always book through Marriott's 800 line. I try to stay at Marriott's exclusively, and when I stay at other hotels I let my travel agent, American Express, take care of it so they can raise hell if necessary (they are effective in my experience). Normally the day before or the day during I call to confirm my reservation, and so far out of fifty reservations have never not found it there. Tomorrow I'm staying at the Torrance Marriott in CA with a reservation I made over four months ago. Checked it and it's just fine but have the conf number in my wallet and also on my laptop. Better safe than sorry is always the bottom line.
My bigger concern is my upgrade on USAirways -- I have confirmed dozens of upgrades w/o problem but there's no confirmation number or any way to independently verify it other than calling them. Most of my confirmed upgrades are done a week in advance, this was done three months in advance (special voucher). I checked about a month ago and it was still there. I'm hoping it sticks.
