Agra to Nainithal
 

Are there over night bus services from agra to nanithal ? How many days are required in nanithal ?

I imagine you'd probably want to go over Delhi to get there.

How many days for Nainital, er, how long is a piece of string? I'd suggest a night or two to see the town and possibly some of its environs. To do some tours of the wider vicinity, could be stretched to pretty much anything, I suppose.