One of Kōya-san's smaller temples, with only 14 rooms, Sōji-in is also one of the most modernised: all rooms have air-conditioning, some have baths (and all have toilets) and there's a lift. All of this is set around a lovely garden, with English-speaking staff and a location across the street from the Garan.
The nearest bus stop is Kongōbu-ji-mae.