Jackie,
Something you will want to attempt to do is get inside a few to see how the layouts suit you. This may require a trip to a dealer that handles used ones, or just doing some tire kicking on your own. The name designation usally can tell you alot if you understand the way they work. My hobby is the 69-82 range and I am to the point that I can usally tell the year from across the parking lot. The advice here is great and though some of us may be long winded (myself included) you will get tons of info.
No matter what you are looking for pre 77
HERE is a link to a site that has many of the models pictured inside and out as well as some in showroom condition and some in deplorable shape. These are not for sale but can be used as a tool for learning or getting a better idea what a 64 Tradewind looks like in and out.
Another resource that you may be closer than you think is a local Vintage Airstream rally. Your Avatar does not have a location in it, but
HERE is a link to the VAC site. If there is a vintage rally near you, you may be able to drop in on the open house that is usally done and see many units first hand with no sales pressure. BTW this may lead you to find a great unit for sale as the grapevine is alive with deals sometimes.
Good luck on your search, I hope you can join the rest of us iin our addiction, to aluminum of course!