Alitalia and Etihad (which owns a minority share of Alitalia) are the official Expo Milano 2015 airline sponsors. The exposition runs until the end of October.
The airlines share a great pavilion that also includes a Premium Lounge where Alitalia & Etihad frequent fliers plus some other passengers (read the entry requirement here) have access to. I spent Friday last week at the Expo and a couple of hours at the Premium Lounge as well, which is a good place for refreshments and charging your cell.
Alitalia and Etihad showcase their products to the general public on the ground floor. You can also find a flight simulator there.
Second Floor (Premium Lounge)
You need to sign in at the reception first before getting access. They will record your frequent flier numbers (at least they did in my case).
They have a properly stocked bar with plenty of adult beverage choices.
The selection of Italian wines is rather comprehensive. They have a long wine list as well.
The lounge service includes lunch between noon and 3PM and dinner between 6PM and 9PM.
You can get some canapes outside of the lunch/dinner hours. I went there after the lunch was over.
You have several appetizer, entree and dessert choices.
Etihad Residence Mock Up
Etihad had their Residence mock up at the show.
Alitalia and Etihad use the pavilion to showcase their products and conduct meetings.
If you have access to the Premium Lounge, it is great place to have a drink or two while charging your phone (or recharging yourself). The lounge was mostly empty the majority of the time I was there and the service is very attentive.
The servers and food are provided by DO & CO. All the other employees with whom I chatted with were from Alitalia or Etihad.