Subpanel Breaker Size

I am curious as what the room is going to be used for. You have about 100ft of wall and 30 receptacles, seems like over kill. Also a 672sqft room with 16 lights.
What is the wattage of the fixtures you plan to use. Even if you took all the lights at 100watts each and the receptacles at 180watts (neither is a residential code load requirement), you would have about 7000 watts/240=29.16 amps. Not knowing more about the room I doubt you would even have that much load. Based on what you listed a 30amp circuit to a small panel would be enough. At 100ft even if you had a full load of 30amps, the voltage drop would only be slightly over 3% and I doubt you will ever see full load on the circuit.