Rooms are indicated on the timetable. With the exception of Tuesday afternoon, all meetings are in large auditorium style rooms underground in Building 40. Most of ours are in Dirac, go down the circular stairs under the blue D.
The Tuesday afternoon meeting rooms are in the main (original, old) complex of buildings.
CERN has a good interactive map website and app to orient yourself.
The other key location is Restaurant 1 (building 501), across the grass from B.40. There is also a very good coffee and sandwich kiosk in the B.40 lobby, that's where to get coffee during the breaks (you pay! Remember there's no reg fee) and perhaps grab a lunch sandwich to avoid the crowds at R1 (after you've had the R1 experience at least once).
R1 is the standard place to stretch out around a patio table with beers after the session on a warm April late afternoon. It's open for dinner, locks up at 10 or 11. Of course there are lots of offsite dinner places, to name one popular place close by (walkable, or 2-3 tram stops), La Meyrinoise pizza place next to the Meyrin town plaza.
