24 or 28 spoke wheels always made more sense to me on a racing bike where aerodynamics matter at lot rather than on a randonneur, where you want things close to bullet-proof. I would never go for fewer than 32 spokes, even though I'm not a heavy rider.
At least around here, your brevet average will largely depend on how fast you can climb on 5-10% grades, for which the spoke count won't matter.