We have front and rear racks and full sets of panniers when needed (i.e., touring, large grocery run), but more typically, DH would use full panniers plus Arkel Tailrider, and I'd just use a Tailrider, since he's the stronger rider. Or I'd use one set of panniers. We also have handlebar bags but only used them for touring as having weight up high isn't as good for bike handling.
If you only use one set of panniers, it's best to use front panniers rather than having all the weight on the rear. With front panniers and a rear trunk bag, like a Tailrider, you can carry quite a bit.
Enjoy your Bike Fridays!
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow