Thanks for the advice.
I've tried a couple variations - my mountain bike and my cyclocross bike. My mountain bike is just clunky on the long gravel flats and climbs. Without twists and turns that force me to shift my weight around, it gets a bit tiresome. I feel like a slug on the climbs, particularly when I find myself staring at my suspension fork.
The cyclocross bike often feels great but is downright scary on bladed and newly graveled sections. The narrower tires continually try to head south to the very depths of the road bed. I cannot get really wide tires on my cross frame - some unsightly rub marks on the inside of my chainstays are evidence of my failure to consider frame flex!
My idea is to try a very wide front and a pretty wide back tire - rather like a 29er but with a road position. I can buy a T800, sight unseen, or switch my cross components over to a Surly frame that a friend wants to get rid of.
Your thoughts are welcome.