Formal:
* Entrance
* Vestibule
* Portico (if it's a covered entryway)
* Lobby (often for larger buildings)
* Hallway (if the entryway leads to a hallway)
Informal:
* Doorway
* Front door
* Entrance hall
* Foyer (more common in homes)
Other:
* Threshold (more metaphorical, referring to the act of entering)
* Gate (for outdoor entryways)
* Passageway (more general, referring to any path leading to another area)
The best word to use depends on the specific context and the desired level of formality.