We would like to visit St. Petersburg this year. I am wondering if June or Sepember would be the better month to go. Are 4 nights/3days enough time to see the major sights without rushing? If not, how many days would you recommend?Thank you.
September. During the summer months the Hermitage is crowded with wall to wall tourists. 4 night/3 days is the perfect amount of time. The Hermitage will take up most of an entire day. On the second day you can check out the rest of the nearby attractions like the Russia Museum, St Isaac's Cathedral, Kazan Cathedral, Church of the Saviour. On the third day you can checkout the palaces outside the city.
The museums in June might be a little more crowded, but given the choice, I would probably choose a date closer to the soltice to see the famous "White Nights" of St. Petersburg. It's a huge city anyway, so it's not as if it's ever not "crowded". If you're into classical music, though, September might be a better time, as the major ensembles take a break over the summer.
I would say 4-5 days are adequate.