I fly the B737-700 and in our company is not advised (as per FCOM) to use the A/T with the A/P disengaged, the only exception is take-off and initial climb.
THe B737-700 has a very strong pitch-power couple so I guess it would be very hard to hand-fly if you are not directly responsible of the thrust setting.
I believe the B777 is similar to the Airbus on this issue, very good A/T system together with a fly-by-wire makes your life easier.
Hope this helps
Ricky