I teach on a bilingual campus.
1. Teacher lounge/lunch if an English only staff member comes in the BIL teachers will switch from Spanish to English.
2. Halls - Spanish teachers speak both languages depending who they are talking to.
3. Meetings - Depends what is being discussed. In our team meetings (3 English Teacher 2 Spanish) it isn't unusual for the Spanish teachers to have brief exchanges in Spanish about things specific to their students usually vocabulary. We pretty much only have 1 type of English spoken on campus (Texan with me throwing in some Maritimes occasionally). We have off the top of my head have 9 types dialects of Spanish spoken (NYC, Puerto Rico, Mexico, Columbia, Guatemala, Houston, Valley (Texas), California, Honduras and those are just the teachers I eat lunch with). They often have to decide exactly which vocabulary to use in lessons.