I assume you mean Bolzano. We drove from Bellagio to Castelrotto which is just a bit past Bolzano. The majority of the trip would be the same. We found it very easy and pleasant. Particularly when we hit the beautiful green rolling hills. We stopped in Verona on the way and had a fabulous lunch and walked around the centro storico. Beautiful city!

It was a bit curvy up to Castelrotto but I suspect you would skip most of that if stopping in Bolzano.

Here is a link to my trip report if you are interested:
http://www.fromhometoroam.com/2012/08/hiking-the-dolomites-2010/

If you're wanting to see more of the Dolomites, I would suggest driving to Cortina D'Ampezzo. The views from the roadside are more spectacular, particularly if you venture into the countryside outside Cortina. I have driven from Venice to Bolzano and also to Cortina D'Ampezzo. You will do more highway driving north of Verona (a lovely place to explore...I agree with jgg) if you go to Bolzano. The road to Cortina is not as much of a highway, but it's still an excellent road with easy driving. Going to Bolzano, you do have the option of visiting wineries in the Alto Adige, near Trento. Of course, if you head to Cortina, you can stop at Bassano del Grappa, the epicenter of Italian grappa. Grappa tasting may be a bit more of a barrier to traveling on than a brief wine tasting.

We drove Bolzano to Venice. Very easy drive. I believe it was under 3 hrs. I wouldn't hesitate to do it again. No problems at all.

There are 2 routes---the scenic and the fast.
I assume you mean the scenic route---I have done that twice.
It incluses Cortina, Arraba, the Sella Pass and Val Gardena.
If weather is good it is quite a trip---have fun !
http://www.slowphotos.com/photo/showgallery.php?cat=4441

Bobthenavigator, michele_d, midhnightsun and jgg
Thank you so much for your quick and very helpful response that helped me make up my mind. I was a little hesitant hearing from some that one ought to avoid driving in Italy.

A potential hazard (to your bank account) are the restricted driving zones in some Italian cities. Watch out for Z.T.L. signs, "zona traffico limitato." Do not drive past one of these signs.