Dolomites Pass - What are the scenic routes?

You can do the "Sellaronda" by car. That is a complete circle around the Sella Massif. 4 mountain passes, tons of scenery. Should take about 4 to 6 hours, with a lunch stop along the way. I've done it on skis in the winter, and should be about the same with a car. Just keep an eye on the weather. Late October you could get snow.

With a base of Ortisei from there it is very easy to drive on the scenic mountain passes, a few start just a short drive away to your East.
This would be an obvious day trip route connecting Ortisei and Cortina both nice scenic towns on opposite ends with a circular route to see a few different passes, this covers the major passes and you definitely can and will make some stops along the way so I would consider this a FULL day.
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Ortisei is in the mountains but part of a valley and is a town reachable from the highway without driving any mountain passes.
The scenic mountain passes are all a few miles more to your East, starting with Sella Pass.

Since you would go West from Ortisei to reach Munich, Verona or Lake Garda ; it wouldn't make any sense to take a mountain pass to these places. The drives to each will not be scenic as it is all highway. I imagine you might be able to find a slower way to go but think that wouldn't make much sense unless you love all day car rides.

For your stop on Garda lake, I'd do Sirmione. Nice village, some roman ruins on the lake, a castle, spectacular site

Torbole is the easiest to get to, just 15 minutes off the main A-22 Autostrada from Verona to Bolzano. It is the far north end of the lake where the mountains drop straight into the lake. Very dramatic scenery.

To get from Ortisei to Munich, your pretty much stuck with the road down to Waidbruck/Ponte Gardena and get on the A-22 north over the Brenner Pass to Innsbruck. You could take a "short cut" straight over the mountains to Munich by turning west at Innsbruck and up through Seefeld, Mittenwald, and Garmisch-Partenkirchen. But it will take longer than sticking to the Autobahn.

Don't forget to buy and attach your Austrian vignette on your way to Italy from Munich.

When I am driving the A22, I always time the lunch stop to be in Isera, a tiny village in front of Rovereto. Wines and food to kill for. My favorite places are Casa del Vino and the Vineria de Tarczal (probably the best quality/price ratio in Italy). The local wine is the strong red Marzemino (opera buffs will remember that is wine served in Mozart's Don Giovanni).