Not submitting a guess yet, but to summarize for those who don't want to read 4 pages of wrong guesses, these have all been swings and a miss...
20th century
4 Queens
Aladin
Aliante
Barbary Coast
Binions Horseshoe
Boomtown
Bourbon Street
Circus Circus
Dunes
El Rancho
Excalibur
Fitzgeralds
Golden Gate
Golden Nugget
Hacienda
Horseshoe
Imperial Palace
Jackpot
Key Largo
Lady Luck
Las Vegas Club
Las Vegas Hotel
Little caesars
Luxor
MGM
Monte Carlo
Nevada Hotel
New Frontier
Orleans
Palms
Planet hollywood
Red Rock
Riviera
sahara
Sands
Silver City
Slots-A-Fun
Spearmint Rhino
Stardust
Stratosphere
Sundance
The Mint
THEhotel
Treasure Island
Tropicana
Union Plaza
Vegas World
Westward Ho
World Trade Center