Although we have traveled extensively, we have always done it by land. SPB, Russia has long been on our bucket-list and my brother recommended a cruise (he had done the port of SPB on another cruise line). After a lot of research, we booked NCL.
I must say, after reading many less than favorable reviews of the SUN, we were pleasantly surprised. Love the free-style concept! Never have to dress-up (saves valuable luggage space).
Liked the buffets (food was always edible although often somewhat bland ... but for the price, I am NOT complaining). There was never a wait in either of the main dining rooms. Many options available ala specialty restaurants (we didn't partake).