Rack or BOB, a triple is definitely the way to go. A "compact" crank has a 34T inner ring while Shimano's road triples have a 30T granny ring and can be easily refitted with a 26T. Either will give you a lower gear than the compact. Your current "braze on" front derailleur tab should have enough adjustment to properly set the FD over either a Compact (50T) or road triple (52T) crank.
You will need a long cage rear derailleur and a new bottom bracket for the triple. A long cage rear derailleur will probably be needed if you go with the compact crank, particularly if you use a wide range cassette.
Assuming your current set-up is Ultegra 9-speed STI, you will not have to change shifters. The left 9-speed STI shifter works for both double and triple cranks.
It's not obvious but 14-15-14 butted spokes are more durable than straight 14-ga spokes. Spokes don't break in the middle, they fail from fatigue at either the head or the nipple threads, both of which are in the thicker sections. The thinner inner section of butted spokes actually serves to reduce the shock loading on the vulnerable ends.
It is true that 36-spoke wheels are more durable than 32 but unless you plan on carrying a huge load, 32's are strong enough.