I just run the fattest tire that will fit under the fenders.
The crushed stone paths in this area vary a lot. Early in the spring, after the snow has melted and before they really dry out, they can be a little too soft to ride with 32's, but for the rest of the year there's no problem with thinner tires. But no matter where I go, I often run into roads with unpredictable surfaces, and wider tires are always better than narrow ones. On sand, it really helps to let some air out.
+1.
While wider tires are not for everyone all the time, given the OP's question, the fattest tire which will fit under fenders, with a conservative tread pattern for low rolling resistance and long wear life, would be my recommendation.