Two in the front of the flight deck (mission commander & pilot).
Two in the rear of the flight deck (mission specialists)
Three on the mid-deck.
STS-71 and STS-61A had 8 on board. STS-71 used special seats on the mid-deck. I don’t know where the 8th person sat on STS-61A. I kinda doubt it was “just have a seat on the floor there, and hold on.” 🙂
Thank you to the Shuttle fleet for all our official and unofficial work in space. I see the light from the space station bright in the night sky.