I totally agree. Staying overnight is an essential part of the experience. Otherwise, it's just more temples, and the rail journey, while beautiful, does take time.

All the temples charge the same and are booked through a central office, the contact info for which is given in all major guidebooks. You get an ample vegan dinner, a room comparable to a mid-level ryokan, listening to the monks chant at dawn, and a vegan breakfast. Then you can start your wanderings through the wooded grounds to the Okunoin. Don't miss the often amusing modern cemetery where recent industrialists have bought tombs marked with the symbols of their industries.