I don't think you will regret staying in Udine. I don't have a hotel recommendation for you there, we stayed at the Hotel San Giorgio, but did not care for it. It was a bit far from the main center of Udine, near the rail station. There were a couple of hotels closer to the restaurants, coffee shops, etc, but I can't remember their names. I will try and look them up tomorrow.
We flew into Venice and had a very reasonable car service (Treviso Car Service
tvcarservice@gmail.com) pick us up and deliver us to Treviso. We stayed at the Arogari B&B, it was lovely and the rooms were modern, beautiful and very comfortable. The breakfast was excellent. I would highly recommend it. We ask the owner to call for a cab to take us to the train station, but there was nothing available for some reason and he took us in his car. The train ride to Udine was very easy. I think we stayed 2 or 3 nights in Treviso, it is a cute small town. One of the days there we used the same car service for couple of stops on the Prosecco road and lunch in Conegliano.
We stayed five nights in Udine, two of those days touring with Sonia. We had also planned to take a train to Cividale on our last day, but spent it in Udine instead. Sometimes we rent a car, but we decided on this trip we needed a guide/driver instead as there was so little information available on the region. It worked out very well for us. We trained from Udine to Venice and stayed there in our favorite apartment for two weeks before returning home. Sigh ...
Hope to go back to Italy in the spring, we ha a fall trip planned but my DH will be having his second knee replacement of the year this summer. Sigh .....
You will enjoy the area and Sonia will be a great help in planning.
Mary Pace