Is it objectively better to visit Tokyo if my goal is to further my Japanese?

I studied two years of Japanese in English University. However, I've taken a gap year and therefore lost a lot of my Japanese speaking ability. I will be finishing my degree in Australia and would ideally like to be a step ahead in my classes (as you know, learning Japanese is a LOT of work). Prior to me going to Australia, I plan on a one month trip to Japan.

So my question is, where in Japan should I go if my aim is to immerse myself in 'standard' Japanese? My plan is one month in one city. Kyoto, Hiroshima, Sapporo, & Nagasaki intrigue me the most. However, I have the assumption that Tokyo would be the best place to immerse myself in the language.

Would staying in one of those cities allow me to be immersed in 'standard' Japanese? or should I plan my trip around Tokyo?