RE: Trek 720 vs Specialized Expedition vs Miyata 1000
IMO assuming all things equal as far as accessories, the 720 and the 1000 weighed around the same. The Expedition was a little heavier, as I recall, being optimized for road
and trail.
I actually have some pretty direct experience since I worked for a Trek and Specialized dealer in the early 80s and owned the Univega branded version of the Miyata 1000*. I've ridden, assembled, sold and worked on all of them, for all practical purposes.
The 720 was the most expensive and generally thought of as the grail
production touring bike at the time. Spec wise, it was Reynolds 531 DB tourist gauge IIRC. Forged tips, great paint job. Lots of euro parts on it. Spec changed by year. It's a quality machine, but a dedicated touring bike. Wheelbase was long, and I felt they were kind of a truck like ride. That's not necessarily a bad thing in a touring bike.
The 1000 frame was made from Tange Champion
#2 , which is equivalent to the tubing set of the Trek. Being drawn cro mo, it's more akin actually to Columbus SP. Also with forged ends. The parts on it were top of the line Japanese stuff of the period, for the most part. Frame weight would have been pretty close to the Trek. It felt much more like a racing bike if you got up and stomped the pedals. In fact you could have raced it with some light sew up wheels.
The Expedition, was as best as I can recall, a slight notch down from these two above bikes in price. It's kind of hard to tell what it was made from because Specialized use proprietary "Specialized" tube sets. Pretty sure it was Tange of some sort, maybe not Champion. It was sold at the time as a sort of cross between a touring bike and a cyclo cross bike. It had 700x35 tires, the first production touring bike to come with them that I know of. The Sequoia was the traditional touring bike.
* The Miyata 1000 and the Univega Specialissima really were the same at the time. There were minor differences in parts spec. The 1000 came with racks, the UV had better pedals, and it had Nitto bar and stem, etc.