If you've been to WDW in August before this, you understand the impact of the intense sun, heat & humidity on your plans.
If you haven't, I can't think of a good reason to request 3rd fl unless it's a special view or QUIET your're after.
Have stayed OKW MANY TIMES. (Since they swapped out carpet for hard floors, we find it is noisier if NOT on TOP floor)
But TOP FL could be 2nd FL depending on room location (Only ONE flite of stairs)
You really can't predict how far your room will be from bus or pool. (HH location or rooms in one of the few elevator bldgs are reserved &/or saved for those needing accessibility first.) Add that to time in parks + waiting for bus or getting to car.
Sorry. 3rd fl in Aug would not be my choice, especially with young kids or anyone with health issues.