We stayed for two nights and got upgraded to a large suite with two bathrooms and view of the Bellagio fountains. As platinum members of Marriott we were given the upgrade, $10 resort credit, late check out, access to the Autograph lounge with free water and coffee, and a couple of other small perks. Worked for us!
The room we stayed in had mini fridge, microwave and bar with sink, two bathrooms, the most amazing bathroom I have ever seen, and the most amazing view if the Bellagio fountains, and strip. We brought out 1 & 3 yr old children and they had the best time watching the fountain shows and playing in the large suite. Also it was about a 7 minute walk to Walgreens and McDonalds which was a great convenience while traveling with two small children.
We hired a nanny for one night from a service called Artsy Nannies (which we were very happy with) and my husband and I spent the evening gambling in the casino. The bartenders and card dealers at each table were engaging and attentive. The casino itself has a warm vibe and a wide variety of games.
What really made the Cosmo stand out is the amazing customer service though. The concierge would check in with us to see if we needed anything and any time we would call we would get a response immediately. We called for a cork screw and had a nice one within 5 minutes, called for a crib...was in our room ASAP, and when we had issues with our bill at the end went to the front desk prepared for a fight and the bill was cleared up right away, no arguing! There is no doubt we will stay here again. The Cosmo def lives up to its 5 Star rating!