Today’s answer straddles two distinct eras and we’ll start with the more modern of the two.
When Bellagio opened on October 15, 1998, on the site of the former Dunes, it would be the last occasion on which Steve Wynn delivered a resort to the Las Vegas Strip that offered extravagant free attractions, including the world-famous choreographed fountain show, which rises out of an eight-acre lake, no less, and which passersby can enjoy without even stepping foot on the property. Inside, the elegant vibe is complemented by the elaborate, whimsical, and labor-intensive displays that rotate in through the Conservatory & Botanical Gardens, not to mention the ornate glass ceiling in the lobby, comprising 2,000 hand-blown glass flowers by renowned artist Dale Chihuly.
Understated in its exterior architecture, which aims to echo a particularly picturesque hillside town located on Italy's Lake Como, Bellagio opened inside with a distinct sense of panache (if less attention to historic authenticity), with lashings of expensive drapery in a gelato flavor-inspired palette that was apparently meant to evoke the sense of a medieval market on the gaming floor. The sense of an old-school private men's club is more successfully carried off in the race and sports book and its bar, however.
On that "adult" note, the resort deliberately debuted without any kitsch gimmicks or kid-friendly attractions; on the contrary, minors were actively discouraged--even forbidden, for awhile, after the resort first opened--from setting foot on property. Even when it came to the adult demographic, although no strict dress code was mandated, it was clearly conveyed by the piano bars and caviar lounge, with its tradition of serving British-style Afternoon Tea; by the leather upholstery; by the look-but-don't-touch price tags in the marble shopping mall; and by scale and grandeur of the last of Las Vegas' signature "free" Strip-side spectacles, that the "theme" Bellagio was seeking to evoke was sophisticated European good taste (whatever that is).
It's fitting that Bellagio and Caesars Palace are neighbors, since when it opened on August 5, 1966, owner Jay Sarno similarly envisaged his resort bringing a new "regal" air to Las Vegas Boulevard, and once he'd settled on the imperial Roman-motif, Sarno paid attention to every detail, from the name (and his idiosyncratic insistence of omitting an apostrophe); to the now-iconic logo and typeface; to the pool complex modeled on Rome's Pompeii Baths and the Circus Maximus Showroom (modeled after Rome's Colosseum), which was even painted blue inside to evoke that authentic "al fresco" feeling; to the toga-like cocktail-waitress uniforms and the "goddess" outfits warn by the female servers in the legendary Bacchanal Room (where "bacchanalian" practices included these goddesses offering neck and shoulder massages to stressed diners).
While this era predates Las Vegas' immersive family-oriented theme frenzy of the late '80s and early '90s, Caesars did not debut without its themed "attractions," including the 18 huge fountains adorning the 135-foot drive up to the front of the hotel, which was lined with Cypress trees imported from Italy. Both the interior and exterior grounds were decorated with $150,000-worth of statuary imported from Peter Bagganti of Florence, while the foyer was fabricated from white marble and black mosaic tile.
Dubbed Caesars Forum, the casino was (and is still, to this day) graced by what was at the time the world's largest crystal ceiling fixture (it's not accurately to be described as a "chandelier" -- see QoD 2/18/11), fabricated from finest baccarat crystal in that classic instance of Las Vegas brazenly blurring the lines in a juxtaposition of classical-Roman meets 19th-century-European-opulence. This was Las Vegas' heyday as a strictly adults-only entertainment destination and apparently it was Jay Sarno who first pioneered the concept of windowless casinos with blacked-out ceilings to evoke perpetual night, since he felt this was conducive to relaxation (in marked contrast to the faux-daytime ceilings in the Forum Shops today).
Of course, it wouldn't be Vegas without the kitsch element, and on opening night the stampede of celebrity invitees were welcomed inside by a busty costumed Cleopatra greeter (Caesars had its King Tut Suites long before Luxor had even been thought of), who could direct them to the "Noshorium" 24-hour coffee shop or to the stage production Rome Swings, which opened in the Circus Maximus and starred Andy Williams, with Phil Richards playing the Caesar character.
And so things have pretty much continued at Caesars Palace, with additions staying in-keeping with the Roman theme, like the 1970 addition of Cleopatra's Barge, the floating nightspot that found a way to make lemonade out of the same lemons that scuppered the original plans for an underground parking structure at Caesars, namely the vagaries and intrusions of the Las Vegas Wash.
It wouldn't be Vegas without some bizarre anomalies along the way, either, with those that spring to mind including when in the 1980s, when the hotel opened an Atari game room, featuring more than 60 video game arcade machines, or the 1996 opening of the multi-million dollar attraction that was Caesars Magical Empire, located by the Race and Sports book what back then was the Palatium buffet. The intricately themed multi-theater show-and-dinner experience, with its cavernous atrium, firepits, live wizard, and real birds of prey flying around, aimed to capitalize on what turned out to be a passing/cyclical public fascination with magic and magicians and it closed at the end of 2002, its former space re-purposed, tellingly, to accommodate PURE nightclub.
