This was a day trip from Osaka. We took the train to Nara to see the deer. Nara is a pretty straightforward place, most people come to feed the deer. There are lots of official vendors selling deer crackers everywhere. I think it's about 150 yen for a pack of 10? Note that the deer can get quite aggressive for the crackers, and showing both hands to them to indicate that you have no crackers is generally the way to get them to stop hounding you.
Tip: I recommend holding onto your crackers until you get farther away from central Nara. The deer farther in tend to be less aggressive.
Most people who come to Nara will visit Todai-ji for the giant Buddha. There's also Kasuga-taisha which is a Shinto shrine and quite pretty. I would say deer is generally the focus of my trips to Nara though.
Bonus tip: I love pudding. Nara has some great pudding in the Kintetsu Nara train station called Mahoroba Daibutsu Pudding. I think they also have an actual store, but I've never been.