We were looking at older Airstreams also, until we went into one and it actually felt too closed in for us. We imagined it raining outside and trying to fit our 2 grown sons and us in it comfortably and changed our mind. I then started researching Avions and went into one and was surprised be the amount of room it has. So we now have a 1978 Avion 30'. The cabnitry and flooring are built very well, and with a rear bathroom there is plenty of room to move around. Ours has 2 twin beds and a sofa bed that we plan on replacing with a dual reclining sofa soon.
So I would suggest spending some time in a few different types before jumping in with both feet.