I'm about to build up a pair of 36h Mavic A319 rims onto Deore hubs for a cheap and cheerful tandem wheelset. The rims feel very strong, if a little heavy at 590g! The upgrade option would be Mavic A719 rims in 36h - 30g lighter per rim and apparently a little stronger still.
I'd be very happy with 36H trekking rims such as the A719, however the availability of suitable hubs in 140mm spacing is difficult. The only option I've found is the Orbit tandem hub that is 40H or 48H.
I'm about to build up a pair of 36h Mavic A319 rims onto Deore hubs for a cheap and cheerful tandem wheelset. The rims feel very strong, if a little heavy at 590g! The upgrade option would be Mavic A719 rims in 36h - 30g lighter per rim and apparently a little stronger still.