In reply to Miskawroe:
I did a route a few years ago starting at Carrezza pass, over the Dent di Diablo and Roda di Vael, to rifugio di Fronza, then up the Santner pass VF past the Vajolet towers, over to Rifugio Principe, did the Cantenaccio d'Antermoia, then walked to Rifugio Tierseralm, did a ferrata of the Terra rossa, then across to the sella pass. Our plan got disrupted by poor weather, for a day otherwise we would have gone up the Possnecker VF across the sella plateau and down to Passo Pordoi (probably using the cable car), and then to walk to the foot of Marmolada to do the west ridge. In the end we walked down to Canazei and caught the bus up to Marmolada. If you did that lot at a steady pace I reckon it would be about right if you've got half decent legs on you. If you wanted to you could add in the VF delle trincee before Marmolada.