One door opens, another door closes

Jesus, I hate this type of puzzle. The first one with (SPOILER)the gates in the mines wasn't so bad, but I just spent the last hour wandering around (SPOILER)the laboratory and I'm getting annoyed. >_> Someone give me the general idea of where I should be going next. (SPOILER)What floor, and what area of that floor are fine.

You're trying to take the lift to floor 70 (I think). It comes from the southern Terminal in floor 68.

Thanks. I should have guessed. :P