Many thanks to Tell The Truth Traveler Bob93_2 for this write-up of his trip!
Stroganoff Restaurant (on Nevsky Prospekt near the Kazan Cathedral) is supposedly where beef stroganoff originated. It is one of the cheaper places to eat. You can order off the menu or have their $5 buffet.
One restaurant we gravitated to because they had a wide variety of food at reasonable prices was the Propanganda Restaurant on the Fontanka canal near Nevsky Prospekt. It has a somewhat different interior.
Miscellaneous Notes:
We ate borscht at many restaurants and it was different in each one but always excellent.
We never had a ‘bad’ meal and were always happy with the food.
Like any big city the food in good restaurants is not cheap but you can have a pretty good meal for under $20/person.
Some restaurants use a different kind of pricing on their menus. The price is in units rather than roubles. It seems to normally be equivalent to the U. S. dollar but it is not exact. Once you see what it is, it is not too complicated but don’t think the price is in roubles.