Painting the inside of an apt

[Mark K.]

I'm in the process of renovating an apartment in a triplex. In regards to painting it, I'm hearing different ways to do it from contractors and such. 

Is it best to paint the bathroom and kitchen walls a different color from the other walls? Or, can the same paint be used? One painter I know says in rentals to use the same paint to keep costs down. 

What are your thoughts?