I loved Orvieto when I visited in the fall of 2014. Lots of sites for a small town, good restaurants, interesting shopping, views, etc. Check out a good guide book or TA about the sites and experiences, as you will need to choose among them if just there for a day trip. The Duomo is outstanding, both inside and out, including the Signorelli Chapel. If it’s a sunny day, the view of the colorful facade of the Duomo is spectacular in the late afternoon, when the sun is low. If you go a very short way down the street coming into the piazza across from the Duomo, there is a great photo waiting, the bright colorful facade framed by the dark buildings at the end of that street. Obviously memorable, at least for me! Also, the Duomo museum, not sure if that’s the name, but it is just beside/behind the Duomo, is excellent. I remember being eyeball to eyeball with some large ancient mosaics, a very impressive perspective close-up. About going from the top of the funicular to the Piazza del Duomo, I remember that when I arrived, a small tour group quickly filled the small bus, and rather than waiting, I walked up the constant slope, dragging my quite-heavy rolling carry-on behind me, so it is doable, but not pleasant that way. I arrived at my hotel soaking from perspiration. There are a couple different bus routes up, not very comfortable when crowded, and sometimes a circuitous route serving local neighborhoods. So, if you like to walk and are not carrying much, go ahead. Otherwise, you might think about a taxi.