Tony: …Due to varying road conditions. I would forgo low spoke count wheelsets. A rock solid 3 cross 32 spoke wheel will be trouble free on RAGBRAI. Remember its a sports tour ride not a road race…
…Why they need a sag wagon with so many wheels in the first place. The answer is they trade performance for durability…
Handbuilt wheels are the way to go for price, performance, durability and ability to repair. If you work with a good builder they can customize to your size and riding styles.
If you are looking for bombproof, affordable wheels that will carry you across Iowa and many miles beyond then consider:
Ultegra hugs, Open Pro rims, DT 14/15 3 cross spokes with brass nipples and of course Velox rim tape. You can pick these up for around $400.
If you want to save some weight and then upgrade to DT240 Swiss hubs or some of the other low weight brands and work with a builder on spoke count and butting options. I would still stick with brass nipples.
I have been pleased with handbuilt wheels from Colorado Cyclist but there are many good builders out there. Prebuilt, low spoke count wheels have already failed you and will fail you again when you least expect it.