both 31 & 31n are busy but then it gets horrible when they merge
if you have all day to get to Silvretta then make a proper day of it by going eastish over to Wengen, then wiggle your way down to Lech - you will find the roads are lovely. You don't need to climb to over 2000m to have fun.
Thanks for the tip wessie, Much appreciated. I think I'll route us so that we arrive into Ittendorf from the north and avoid the lakeside route. The next day we ride to the Sivretta, then onto Landeck, down the B180, SS40 and finish up just short of the Stelvio at Trafoi. That's about 300km (180 miles) or so going the direct route, I like the look of the Wengen, Lech route, just have to check how much extra mileage it will involve. Again, thanks for the tips!