A better title for this thread would have been Busy bars and restaurants.
Rover1) Usually my restaurant is quiet at lunch time but business picks up in the evening.
2) Business is usually slow on weekdays for most of the restaurants in this town.
3) What night is the busiest for this bar?
4) On what night does this bar get crowded?
5) This bar is busy/happening on what/which night? This construction does not sound natural.
Student or Learner