The Atrium at Bellagio is always a must do whenever I visit Las Vegas. Best of all it's open 24 hours and FREE.
The beautiful floral displays are frequently changed out according to season or holidays. I have been fortunate enough to visit when they are not changing out the display which can be the only negative & inconvenient aspect but you can always check out Bellagio's website and look up their schedule to see if it will coincide with your visit.
Since this hotel is known initially for it's Gallery of Fine Art, there is always a famous artists painting rendered entirely out of flowers & live plants portrayed on a massive picture frame. It is indeed a work of art whatever it may be.
So far I have visited only Summer and Fall. Would love to see what Christmas is like one of these days. Simply stunning. I am always at awe here.