Originally Posted by
indyscott
To answer your original question, I would not consider it "convenient" to routinely take the monorail from the Renaissance to meet up with friends at City Center.
The station is close to the Renaissance, but it runs along the back of the hotels on the opposite side of the strip from CityCenter. Therefore it would still be quite a walk (15 mins?) from the nearest Monorail station to Aria.
As others have suggested, the Cosmopolitan would be your best bet if you are set on staying in a Marriott property and traveling with friends staying in CityCenter.
There are other nice Marriott properties around town (including the Renaissance), but IMO, you'd be better off getting a rental car for transportation to the strip if staying at any of those.
BTW, driving on the Strip could sometimes be more time consuming than taking the monorail due to traffic. So, it you don't mind the walking to and from the monorail then it may be OK to stay by the Convention center to save a few bucks for the other expensive. If money is not issue then Of course Cosmo is the perfect choice.