Traffic ghastly along the B31 north shore, as others have said, but it's effect rather depends where you are based. We usually stay down on the lake at Immenstaad am Bodensee, the Hotel Seehof.
You can always take a few boat trips instead. Lindau makes for a pleasant stop, or try the Zeppelin Museum at Friedrichshafen.
Out on the bike, we like the rides around the Ober Donau. Head to Tuttlingen, then east along the Danube (Donau) valley. If you cut north up the Barental, you can ride over the high massif & rejoin the valley, then on to Sigmaringen. Popular with the German bikers, but make sure you are fully fuelled up as availability is limited in agricultural areas. If you enjoy wandering around historic churches, then the lavish Baroque interiors at Zwiefalten & Weingarten are worth seeing. For a slightly longer excursion, try Rot a d. Rot, just west of Memmingen, then Ottobeuren, to the south-west of M - the Abbey Church is spectacular & the town makes for a nice stop too, with a great Pizzeria just below the Abbey or a Brewhouse further downtown.
Have a good trip.