Reading about touring bikes, I came to the conclusion that if Velocity rims were good enough for Peter White, Wheelbuilder.com, Co-motion etc to use and recommend then that was good enough for me.
I've just had build up, some touring wheels for my Surly Ogre. I went with a Son28 and Rohloff (both disk braked), 36 spokes (Sapim CX-Ray) and Velocity Dyad rims. I went with the Sapim spokes and Dyad rims as I wanted to slightly counter the Ogres hefty weight hopefully without compromising the strength of the wheels. My choice of hubs hasnt helped in the weight stakes. My Ogres nearly complete and I cant wait to rock n roll. My post is not to suggest you follow in the tyreprints of my dream build but merely to echo the 36 spoke mantra. As to what you've already got..... ride em till they drop would be my advice with the caveat of keeping them maintained with a tension check before each tour. No point in going to the expense of new wheels till the old ones die (unless of course you fancy a bit of retail therapy which we all enjoy from time to time)