We use this route: At the junction of the A26 and A1 take the A26 towards St Quentin, off the A26 at junction 11, direction Soissons, on the D1. Continue on the D1, by-passing Tergnier, and carry on, by-passing Soissons (some good supermarkets just off that by-pass). Continue on the Dl direction Troyes via Chateau Thierry, Montmirail - which is the only wiggly bit through the village, Sezanne, by passing the town then take the D373 direction Troyes, via Anglure, Mery sur Seine then just after Mery sur Seine take the N19 direction Troyes. We then continue cross-country to Dijon usually, but you could then take the A5 from Troyes to Langres.
It's quite a quick route - and we've been much further south, generally stopping overnight at Lac de Panthier at Vandenesse