The Nord - Pas-de-Calais has produced a pdf guide to Great War sites in the region that includes four themed trails. The first follows the front line, starting with a little cross-frontier diversion to Ypres, then Fromelles - Loos - Notre-Dame-de-Lorette - Vimy - Arras - Bullecourt - Flesquières - Hébuterne and finishing at Ayette Indian and Chinese Cemetery.
The second covers both the war of movement of the first few months of the war and the subsequent German occupation. It starts in Comines, before going through Lille, down to Cambrai, then back north, finishing at the French war cemetery at Assevent, near Maubeuge.
The third covers the rear areas and the Channel coast. It starts at the monument to the Dover Patrol at Sangatte, outside Calais, before heading southwards Wimereux - Terlincthun - Boulogne - Etaples and finishing at Haig's statue in Montreuil-sur-Mer.
The final tour covers the reconstruction of the areas devastated by the war. Unsurprisingly, it covers much of the same ground as the first, but with a larger emphasis on rebuilt towns and post-war cemeteries. Starting in Méteren, it visits, amongst other places Bailleul, Lens, Arras and Cambrai, finishing in Tourcoing.
The website version links to information (in French) about each and every site on all four tours. Unlike the shorter Artois tour, there is no time recommendations - you will obviously want to go at your own pace - but there's enough here to keep everyone amused for a good week, if not longer.
Photo: the Canadian memorial at Vimy, from wikipedia