Olives is a very nice restaurant bar that is located in the Bellagio.
I think they can get pretty busy here during peak dining hours so I would encourage you to make a reservation. We did so using OpenTable.
Olives has indoor seating as well as patio seating. You can also choose to sit by the bar. The indoor area is very relaxing with little overhead lighting letting the natural light from the patio serves as the main source. The outdoor area is great as well seating around 10 or so groups/tables. There were large parties as well as just couples dining outside. This is probably the best place to eat as you will be able to see the Bellagio Fountain Show during dinner. This area is kept very cool with umbrellas and misters throughout.
I would say this place is pretty formal in terms of attire.
The menu and service here are great with a nice selection of flatbreads. They provide you with a drink and dessert menu that is presented through an iPad. A very modern way of dining and a definite need at more venues. Service was prompt but not overbearing allowing us to dine at our own pace. You are served bread and olives while selecting what you would like to eat. I had the flatbread and it was really good and refreshingly light.
I would suggest coming here for a nice dinner or even for a few drinks at the bar with its great selection and appetizing bites.