Ah yes, the "champagne brunch" at Imperial Palace. We recall phoning to ask what "champagne" they served, during a survey to determine whether any champagne brunch in Las Vegas actually served real Champagne (i.e., from the official Champagne region of France) and discovered that only one, namely Bally's Sterling Brunch on Sundays, served the real McCoy, while most serve cheap, sweet Californian bubbly, or at best an okay Spanish cava. The response from the IP, however, indelibly printed in our memory, was, "The cheapest stuff you can get; you know, it comes in a keg."
With that sadly an option no longer, and the much-mourned Commander's Palace in Desert Passage (now Miracle Mile Shops) now a distant memory (the Friday Champagne Jazz Brunch was discontinued in 2006 and the restaurant closed in early 2007), there is only one weekday champagne brunch option available, but as a substitute for the IP, we'll definitely take it.
The buffet in question is Wicked Spoon at the Cosmopolitan, which is among the best in town and from Monday through Friday, from 8 a.m. to 2 p.m., serves brunch for $24, which includes a complimentary glass of sparkling wine, mimosa, or Bloody Mary. Upgrade for $9 and enjoy bottomless quantities of any of those. On the weekend, the price of brunch (which is served until 3 p.m.) goes up to $33 and does not include a complimentary cocktail, but the $9 bottomless drink option is still available.