I just stayed at Cosmo last week. I have booked the City room 3 times now. Twice been upgraded to a 1 BR studio with a balcony. One time a wrap around. I have not heard anything about only a 1 room upgrade? I personally think the wrap around is way to big of a room unless you have 10 guys crashing on the floor. I would take a middle balcony studio any day of the week over looking Bellagio.
It is all who you get in at check-in. If you get someone experience and later in the day helps for big room upgrades.
Platinum's can use any invited guest line at check-in, Wicked Spoon etc. We get no short cut access to Marquee which is the night club, which is the hottest nightclub in vegas right now on Mon fri-sat nights. Check it out monday night around 10-11 sometime. Crazy!!!