Also have some backpacking background (100% of AT, ~25% of PCT), but more in bike touring.

I use Velocity Dyads, 32 double-butted spokes, and XT hubs. I'm a fan of all three. You're definitely on the right track with getting Schwalbe Marathons, 32 mm. If you're sticking to pavement, I recommend the Marathon Supreme. I had a rear tire last 8,000 touring miles before I ditched it (and it could've kept going!), and I notice no difference in puncture protection between the Supreme and the Tour Plus. The biggest difference is the Supreme is noticeably smoother, lighter, faster on pavement.

I'm not a big guy (135 pounds) and I pack relatively light. Maybe 36 spokes is better for a guy who weighs 180 pounds and brings 50 pounds of gear for a total of 230, compared to my 135 + 30 = 165 total. There are plenty of guys that weigh more than 165 pounds on their own, riding carbon road bikes with 16 spokes on the wheel. I feel like 32 is plenty.
32 front, 36 rear would be an excellent compromise.