From what I remember the pull-out is on the narrow side, but length won't be an issue at all for a nine year old. Narrow, as in maybe a little wider that a couch? Now as an adult I "can" sleep on a couch. So I think it would be just fine as long as he is not a restless or wild sleeper. A twin bed it is not, but still very usable! It pulls out of the area under the tv. As long as it is folded in during the day you should have no problem with the space in the room. We actully left it out all the time (10 days). Plus we had the matress from the top bunk laying on the floor... none of my kids were big enough to trust on a top bunk. It was fine for them to get around and for us to tuck them in... we however dressed them in our room so three bigger kids would be crowded getting dressed maybe if the pull-out was left out. One at a time... just fine though.
You may also want to consider moving the table and chairs out of the kids room if space is an issue... we set them up on the top bunk since we brought that matress down (to make room). Staff never had a problem with it... just made the bed that was laying on the floor.
Hope this helps a little. We spent 10 days last October with our triplets (then 2 yrs old), my mom (grandma to help), and husband and me. We never felt the suite was too small and loved the experience. We will stay there again next time we go with kids... this next trip is just us parents though!
Julie P.