Which airline do you take?
PEK Hilton is somewhat close to Terminal 3, but not Terminal 1 or 2.

I didn't like the PEK Hilton.
You need to walk around 500 m from terminal 3 to get there.
You need to walk another 10 min from reception to your room.
The ventilation system made quite some noise. Otherwise, it looked quite modern and clean.
With a 7.55pm arrival, you may be able to check-in by 9pm.
With a 6.25am departure, you need to leave by 4.30am at the latest (its 7 hours and 30 min max at the hotel). You need to check in your bags, pass thru security, take the train, pass exit immigration ... It all takes time.