I love all of these places!
The elevator & On-call rooms forever! xD

I think there´s gonna be a fight just between elevator & on-call room anyway :D

hard! but it is in the elevator the romantic and the funny scenes are!

and The Tunnels :D

Especially if I hitch a ride with McDreamy!!!!

Proposal ppl! there was a friggin marriage proposal in the elevator!! xD

Also The Bridge, On-call room.
Nice question, btw

I love the elevator because of the fact that Derek proposed to Meredith in an elevator.

I love the bridge when Derek begins to think and look at the skyline. (:

There're always great scenes, very emotional, there. (Derek seeing Meredith crying because she doesn't want her mum to die alone in saison 2, Addison crying and Meredith showing up not on purpose in saison 3, Izzie and George's silent moment, after he remembered they slept together the night before in season 3, Alex and Addison sleeping together in saison 3, meredith hiding from her father and Christina hiding from Marlon in season 3 as well, etc etc... loooots of good scenes there ^^)

Personally I simply love all these places...elevator is definitely the best, but it has just so many votes :D The second choice is harder, there are places where serious, emotional moments happen (like the OR, the ER, CT or the bridge....not always though) and then the funny places (cafeteria, locker rooms, on-call room, OR schedule board or the tunnels...). It´s really hard to choose, but this place has no votes so far and I love it - scrub room!
One of the most adorable scenes - Pick me, Choose me, Love me happened there for example.

Also, the ventilation room where Cristina and Owen had that sexy kiss and Izzie told Cristina about her cancer.