I'm not familiar with the area and any insight would be great. Thanks!
It's pretty simple and straightforward. What time of year? It will be about six hours with a stop. Most of it is on interstate highway through wide open desert. No mountains of any kind after you cross Parley's Summit right out of Park City. If it's winter and you want to avoid that, you can go around on I-84 and have no mountains at all.
Main route is Park City to Salt Lake City on I-80, then picking up I-15 to I-84. In Twin Falls hop onto US93 and drive the final two hours up to Sun Valley. It's a notably scenic route but you do have great wide open vistas of vast desert and distant mountains the entire trip.
"It's a notably scenic route"
I think that's meant to be NOT a notably scenic route. I hate that drive! Boring, always seems twice as far as it actually is. Probably partly due to the fact I'm usually looking forward to being in the Sawtooths.
Yes, with the exception of I 84 through Weber Canyon and a section between about Tremonton and about the Idaho State Line, I-84 to Twin Falls from Park City is rather boring. Otherwise, it's lots of wide open spaces, farm land. That said, if you haven't experienced that kind of landscape, you may find it scenic.