「どっち」 is rather a colloquial expression. 「どちら」 is formal and 「どちらが西ですか」 should be accepted. Reported on Oct. 28, 2017.
Can it be used "--doko desu ka" as well?
I don't think so. どっち is 何方 - literally "what direction" and どこ/何処 is 'what place'
Just to add to what airza said, "nishi wa doko desu ka?" would mean "where is North?" which is a nonsense question, since North is a direction, not a place.
"Nishi" means "west"
This was my first question where I was expected to write in Japanese. I wasn't prepared. But I will be now.
This reminds me of Luffy