IMO, one of the best SW character interactions can be when the two Stormtroopers are on patrol.
They exit the Stromtrooper Barracks located inside the Launch Bay on the hour and half hour and begin with a quick patrol throughout the Launch Bay. They will usually make a stop at the Celebration Gallery located at the far end of the Launch Bay. They then exit into the Animation Courtyard often stopping directly in front of the LB between the main LB entrance and merchandise shop to do a short M&G routine. The skit begins with the two Stormtroopers selecting a few Guests to participate, which includes a rare photo Op with those Guests. It's very amusing depending on the people selected. It's not scheduled and doesn't always take place. Afterward, they continue on patrol towards Center Stage stopping frequently to interact with Guests. The sessions last about 25 minutes.
Another little known mini-event is the procession to and from the stage by the SW characters performing in the "A Galaxy Far, Far Away" shows. A Magical Moment will often occur when they reach the entrance to the Launch Bay during the return procession. It'll be between one of the characters and a lucky child guest, be on the lookout.