Remember that when you test drive an EMPTY Class A, it may rattle more, accelerate and stop differently, and handle winds different than when it is loaded for travel. The seating position, visibility, and control location will be the same but that is about all that you can really tell from a test drive of an unloaded coach. You may get blown all over the highway in an empty coach and it may be rock solid when properly loaded. Also if you plan on towing, you will not be able to tell the performance impact of a vehicle in tow.
I think a test drive is important but keep in mind the limitations of what it will tell you.