One of the top bucket list items to see in Vegas. The conservatory is so nice and the Bellagio switches things out seasonally. Chinese New Year is a big one in January/February. Cherry blossoms is big in March/April for Japan. There are so many different things that are put here during the year. Definitely go super early during the day (or stay up really late) and check it out. The foot traffic on the weekends can kill any good picture to take.
In addition, check out the hotel lobby. They have some blowing glass there by David Chihuly and usually something there below. Also, take a look at the chocolate fountain that is down the hallway. Super cool where one can grab some gelato as well.