Las Vegas is a very strange place. Many would say that the way it gets its reputation from the early ties to organized crime, exotic dancers, millionaire hermits... but I believe people remember the varied themes of each hotel. History is wonderful but people are visual creatures. Themes have been a focus of hotel creation during the last few decades as a means to draw a 'different' type of crowd.
First of these to create a theme would have to be Circus Circus. Sure, it's a kiddie place with midway games and pink all over but it did draw people with circus shows and stuffed animals. Then I would say the Excalibur took the next step. They were created by Circus Circus properties and actually gave the impression of castle walls with turrets. The only problem is getting from one section to another as an employee but the theme works. They even carried the midway idea over and included a weight guesser.
The Circus Circus company then went one step further and decided to bring Egypt to Las Vegas with the creation of the Luxor. The pyramid shape had early issues as drivers reported being blinded as they passed the area so a change of reflective glass was chosen (and now sometimes has advertising on it.) The high-powered beam shooting through the top has been seen as far away as space. There is some interesting history of the hotel about it being cursed for trying to bring such a place to Las Vegas. During the first year of creation, many engineers reportedly saw cracks in the foundation widening. Many said the hotel was sinking others said the weight of the top was pushing the base out due to it being hollow in the center. More recently, the hotel added other sections around it which could be seen as lending support to the base... if you are a conspiracy theorist.
The MGM Grand popped up in 1993 and went in as a partner to build the New York, New York hotel across the strip from it. The company would later buy the partner company and the other half of the hotel. It is the only hotel in Las Vegas to actually show a skyline of any city and has a functioning roller coaster running on the outside. I still wonder how it functions internally as it is a collection of actual New York buildings. I do wonder if the rooms are themed or if they have a view from each of those little windows. Anyhow, after the purchase of Primadonna (the partner company), MGM went and purchased the Mirage properties and Circus Cirus properties (under the Mandalay Bay name.)
The MGM itself is rather interesting as it isn't the original. Many people visit and ask why it took so long to rebuild it after the fire. The MGM actually sold their hotel to Bally's after the destruction and lawsuits following the fire that claimed 84 lives and injured 679 in 1980. They actually decided to avoid the hotel industry entirely... until they decided to build the largest hotel on the Las Vegas Strip. The MGM Grand is actually built on an existing structure, the Marina hotel. The newer structures took over the Tropicana golf course and included a theme park. Opening with a Wizard Of Oz theme, the hotel changed direction away from family marketing with the removal of the theme park and Oz areas. Not often mentioned is that if you look directly down on the hotel room area, it is in the shape of a crucifix.
A cross would be the first obvious use of symbology (although not often cited) in Las Vegas hotel structures but it would be wrong for me to exclude the Imperial Palace. It was long rumored that the building was slowly being shaped as a swastika. Now, you won't see many photos of it from above but this longstanding rumor still exists due to the history of late owner Ralph Engelstad. Essentially he was given the 2nd largest fine against a Las Vegas hotel ($1.5 million) for disgracing the industry with Hitler parties in 1986 and 1988 (Engelstad was the owner of a massive Nazi and World War II memorabilia collection.)
All in all, some people will see the glitz and glamour of 'Sin City' in television specials, shows and movies but there is a lot more in the buildings millions come to visit every year.