2 days itinerary in the Dolomites with a car

Ortisei and take the lift to the Alpe di Siusi for some easy walks with fabulous scenery.

As Sam suggested, start in Ortisei. You can visit the Tourist Office there for advice. Each of the villages — Ortisei, Santa Cristina, and Selva — have their own charm. You could drive the valley up to Selva and back. There is a panorama walk between the 3 villages, about 6 miles total. Super easy, paved, and you could do a small segment if you like. The TI can tell you details. There is a very nice walk at the top of a funicular at Rasciesa. It is about 30 minutes to a mountain restaurant (called a rifugio) where you could lunch, a charming chapel is 15 minutes further up that trail. It is a gravel trail with some flagstones on steeper portions at the start. Requires good tread on your shoes.

I would go up to the Alpe di Siusi from the cable way to Compatsch as your second day. The base station is near Siusi (closer to Bolzano). You can walk a bit on the Hans and Paula Steger Trail. Very easy out of Compatsch to walk to Hotel Steger-Dellai and back to Compatsch and the cable way is magnificent! Ample parking at the base.

Since you have a car, I would drive to Cortina on another day. However, not on a weekend, as many car and motorcycle clubs enjoy driving through the Dolomites in groups. They may do this during the week, but I white-knuckled my drive on a Sunday afternoon.
There are several routes - the scenery is stunning!

What Gail says is true and not limited to weekends in good weather. I would personally not drive that pass due to the buses, winding and narrow roads, and abundant motor cycle riders. You can enjoy your time in the area without adding this stress.

This isn't a hike, but downtown Bolzano is fantastic! Great energy: markets, shopping, etc. Make sure to see Otzi the 5300 frozen guy @ the Museum of Archaeology in Bolzano.

For easy hikes, definitely Alpe di Suisi.