Japanese would say "I don't go" (ikanai), as nothing else can translate the never here (you can't say "I'm always not going"), but also because there is no future tense in Japanese.

Other possiblities include "kesshite ikanai", "zettai ikanai" or "zenzen ikitakunai". Litterally it means "I really don't want to go" or "no way I (will) go there" which is what "never" means here. I was also told that "itta koto ga nai" had the same meaning ! It's even more confusing as it really means "I haven't been there" (past !) while we insist on the future with "will" in English.

By the way, I asked more people about "kaika" and "kaijou" for downstairs and upstairs and was told that only very old people use it. Bad luck, I thought we had something here. That tend to confirm that Japanese language is getting narrower among young people.
Nevertheless I found one more common use of "soko" (bottom), in addition to the "bottom of the ocean". You can say "hako no soko ga nuketa", "the bottom of the box fell out". So it only works for something flat lying low, not the lower part of a height. But it's good to know.