The Short Answer
Most visitors should not stay overnight in Nara, and the ones who should know why they want to.
Nara is forty-five minutes from Kyoto and about the same from Osaka. Its major sights — Todai-ji, Nara Park, Kasuga Taisha, Kofuku-ji — sit within a walkable area and can be covered properly in five or six hours. That is why the standard plan is a day trip, and the standard plan is right for most people.
What an overnight buys is the two hours at each end of the day that day-trippers never see.
By nine in the morning the first coaches have arrived at Todai-ji. Before that, the park belongs to the deer, the joggers and the people who live there, and the Great Buddha Hall opens early enough that you can be inside it almost alone. After about five in the afternoon the same thing happens in reverse: the crowds drain back to the stations, the light goes long across the park, and Kasuga Taisha's stone lanterns look the way the photographs suggest.
If those hours matter to you, stay. If your Japan itinerary is nine days and you have not seen Kyoto properly, do not.
The compromise nobody mentions: go early rather than staying late. A first train from Kyoto has you in Nara Park by eight, which captures most of the benefit without giving up a night.

Nara Early Morning Deer Park & Todai-ji Walk (Beat the Crowds)
A top-rated Nara experience, bookable directly through AsiaByLocals.
From USD 48.73
4 hours
