To your 1st comment- plan on getting 2 of 3, unless you want to spend serious coin. Whichever 2 you get, dont doubt your decision.

To your 2nd comment- Old can be fine. I have a lot of old wheels. New means there will be less issues, typically. Cost is also higher, obviously. Older wheels, unless they have been properly taken care of, typically have pitting on the cones of the hub. The cones are one of the 2 points inside the hub where the balls make contact, and pitting is little wear areas that are like small gouges. Pitting will make the hub feel rough as the rolling surface is no longer perfectly smooth. I have a 25 year old wheelset with slight pitting and still enjoy them a ton, even though the hubs and rims are pretty entry level.
New wheels allow you to not care about possible pitting and the wheels will start out straighter than used wheels(typically) due to lack of use.



You should set a price level and start from there. Excellent wheels can be had for $1000, $500, $250, or even $200. The lower costs just mean some tradeoffs which typically dont make for a 'lesser' wheel, only less convenient maintenance or heavier weight. With that said, a lot of times a heavier wheel is also a stronger wheel, so that negative isnt really a negative.
More money will get you better quality hubs. Cartridge bearing hubs are typically significantly more expensive than loose ball hubs. I use all loose ball hubs and they are cheaper in cost, but work perfectly fine. All Shimano hubs are loose ball hubs, fyi. Better Shimano hubs will have better rubber seals to keep out gunk and moisture from the bearings, and they will also have a higher quality bearing surface(the cup and cone area is harder for less potential damage).
I have 30 year old Shimano Ultegra(600), new Shimano Tiagra, 25 year old Shimano Exage, 25 year old Shimano RX100, and a handful of Japanese hubs(Sanshin and others) from the 80s. All of them spin great. The only difference is the quality of how each keeps water and gunk out of the bearings.

If you used Shimano Deore or higher level hubs- your wheels would have excellent hubs in both quality and weather seal.
Sun CR18 rims are low cost, but I have a set and they built up great. They look period correct on an older steel touring bike too.
Other rim options- Velocity Dyad, Mavic A319, Mavic A719. These are 3 commonly mentioned rims for touring.
Whatever rims you choose, just make sure they properly fit a wider tire. No need for very narrow rims that are meant to only hold racing tires.

Straight gauge spokes arent as strong as butted spokes because the butted spokes can flex more and absorb impact better. But ultimately, both should be really good if they are built well.
Below are a couple suggestions to give you an idea.


https://www.universalcycles.com/wheelkit.php This will allow you to custom spec your wheels. Wheelsmith butted spokes are the least expensive butted spokes they have. You can compare Shimano Deore hubs with White hubs, King hubs, Velo Orange, and more. They have the CR18, Mavic A319, and Velocity Dyad rims too. Select brass nipples.
There are so many options, it can be tough to even narrow down options. but 36H hubs, to me, are best due to strength. That will help eliminate a lot of options that are less spokes.