[CR]Wheelset and tire needs for a light touring bike

I am working on a project bike (a light tourer for my wife), and I am in need of a wheelset and tires. The frameset is currently set up to take 650B wheels, but the braze-ons can easily be changed to accommodate any of the wheel options below before the final paint job is added. Sooo, I am in need of sources (and/or opinions) for any of the following options:

1 pair of high quality 650B (584 mm) rims and matching high quality tires

or

1 pair of vintage looking 650C rims (571 mm--the current 650 racing size--I think) and a source for wider tires such as 28 - 32 c or larger (I know that there are plenty of narrower tires available in this size).

I am open to clinchers or sew ups as well as a complete wheelset.

ALSO, I've wondered if going down to a 26" (559 mm mtn. bike size) would mess up the way the bike was intended to ride and handle. Any thoughts??

Thanks,

Rick VerHoeven

Twin Falls, Idaho