Tipping (bribing) tips for a newb?

Hey all, I'm heading back to Vegas for a business trip, staying at Bellagio. My room was booked through the mgm website to get convention rates.

Any chance I might get a room upgrade if I tip someone? Or are business trips usually automatically put in a certain wing?

If an upgrade is possible, how should I go about trying to get one? Hand over an extra 20 or 50 with my credit card at check in and politely ask if any upgrades are available? Hand it over and say nothing? Wink? Waggle my eyebrows?