Hello Chris,
Welcome to the Forums -- may your Airstream interests be kept alive! Many happy returns (to this website that is...).
It's interesting trying to interpret questions that various members ask. Yours seems straightforward enough but please speak up if this isn't what you wanted.
Vintage -- I don't know that there is a single site. There is an unpredictable scattering of floor plans posted by only a few members here. There is one good photo site for 1979 and earlier:
http://www.vintageairstream.com/archives/index.html Be aware that the photos are of the specific trailer(s) available and may not reflect all variations possible; eg, double bed vs. twin.
Just to cover the waterfront -- New:
http://www.airstream.com/product_lin..._trailers.html