Keep the mid way and set a volume limitation to avoid being off caught by sudden loud sound which could be potentially destructive to hearing.
Talking about tones, I hate vibration, so my silent is complete silent. If I don't turn on tones, I would ignore everything coming to my phone if I don't use it, everything, including phone calls.
One notch under half way. Not real loud but enough where I can hear it during the working day. At night the email notification does not wake me but is loud enough that I can hear it. Never use vibrate unless in a meeting.
Same here. If I need it quiet I have it on vibrate, but if not then it's on full volume so that I can hear it when I'm out and there's always some noise around or even at home and the phone might be in another room.