Ideal Time To Visit.
I landed in Prague on a Monday evening, leaving on a Friday evening in mid-February. I was lucky with the weather, not too cold and, more importantly, it was dry!
Spending the week there seemed to be the best option, it was reasonably quiet and it was only on Friday afternoon that most of the tourists (including the archetypal English stag parties) started to arrive.
The four full days were more than enough to see the sites of the city and take a trip out to Kunta Hora to see the 'bone church'