Fireworks at race finish,or triggered by time/date.Dynamic track lights, inc flags, internal building illumination, flashing lights on emergency vehicles etc.
Realistic water with reflections and different presets (sea, pond, lake etc).Realistic flags governed by wind speed and direction.Animated crowds, marshals, and other track personnel.Animated helicopters, blimps planes etc that can follow patrol paths (see the recent Goodwood hill climb update on RD).
Assetto Corsa was very stale in vanilla form but with the CSP it's a match for anything out there. Click to shrink.I too love the race-day atmosphere in the GRID and Shift games.