We drove within a 6 hour radius, and the only downside was weather, but you can work around it. It’s not really a surprise…you know when the blizzard is coming. 
In 2014 we drove home from Chicago unifieds in a crazy blizzard. What should have been a 6 hour drive took nearly 12 - most of it going under 40 mph. BUT we made it back - which was important b/c I needed to get back to work on weds. Friends who were supposed to be flying back on tues were not able to get out until Thursday evening- so missed 2 additional days of school/work etc. I think driving gives you more independence - but I have lived my whole life in the “snowbelt”, and therefore very comfortable driving in wintry conditions.
We live in the midwest, and drove to every audition. All but 2 schools were within a 7 hour radius - the 2 outside the radius were scheduled at Unifieds in Chicago. Drove through some dicey weather - but I preferred that to air travel. Added bonus - we could pack as much as we cared to with no additional baggage charges!
The weather in Chicago this year has been considerably different than years past; we’ve had little to no snow, and only a handful of truly cold days so far. I know it’s like this all over the place too, so it appears that knock on wood traveling this winter will not be as big of a pain as last year or the year before. Also this thread is making me very grateful that I’m just a fifteen minute el ride from the Palmer house, I could commute to unifieds next year!
This year, those of you traveling under your own “steam” may want to utilize a vehicle like Chitty Chitty Bang Bang so you also have the option of floating to auditions. “What is this about?”, I wonder as I sit here in the midwest on December 27th with sheets of rain pouring outside my window in the 65-degree “heat”.