I’ll play, since my late night thoughts go down these lines.
Frame: Either L’Avecaise or custom LyonSport from Jeff Lyon. I’m also intrigued by Terraferma, but Lyon is more likely since I could actually visit him with my current fave bike for fit consultation and conversation about the points of vacillation below. Definitely a sport tourer geometry, but long-range gravel isn’t a requirement.
https://www.lyonsport.com/frames-0
Terraferma Cycles
Color: probably something slightly metallic, single color. Lyon’s Flickr album shows many delightful examples:
https://www.flickr.com/photos/30361758@N08/
Wheels/Tires: I vacillate between 700C and 650B, tires from Rene Herse. I ride 62-63cm fames, and the 650’s can look a bit awkward with a big frame, but love their comfort on our crappy pavement and nimble feel. Not sure if fat enough 700’s would sacrifice that nimble feel. Shimano hubs - 600 tricolor or Ultegra with my custom 8-speed cassettes. If 650B, I already have the wheels!
Group: Continue with my beloved Sachs Ergo 8-speed (lots of spare brifters in the inventory), 110/74 triple crank like the Sugino AT or Specialized Flag on an SKF square taper BB.
Saddle: Also beloved Gilles Berthoud Aravis, color based on frame, etc.
Brakes: Another vacillation - cantis for fat tire installation ease, or brazed-post centerpulls for easier setup? Fenders are easy with either.
Stem, bars: That chrome fillet-brazed steel stem on the reworked Lyon in the latest BQ is gorgeous! I’d like to try Randoneur-bend bars, if the geometry can be worked for my short torso, bar height, and their longer reach compare to Noodles.
Headset: Something with roller bearings, assuming that works with the stem above.
Bag: Love the convenience of the rando front bag on the Miyata with it’s Gugificazione lower trail, so another of those, custom built by Dave Cain at Waxwing.
Waxwing Bag Co. - Home
Fenders: Enough room for Berthoud stainless, but they’d be seasonal, since we often put two bikes in a car for transport to 3-season rides, and fenders really complicate that. They have worked well when the Marinoni is in 650B configuration for the winter.