I live in Chicago and have put about 8,250 miles on my LR RWD Model 3 since taking delivery in mid-November.
This includes roundtrip to Atlanta driving through the hills/mountains in southern Tennessee and more notably roundtrip to Breckenridge.
My drive to Breckenridge was through a blizzard where the highway was ultimately closed in the opposing direction upon my arrival in Silverthorne. In the future I plan on making this trip with snow tires, but this time around I was confident in the performance of my brand new all seasons. I did not really slip or slide, although I was not driving very fast due to poor visibility - at times I could not see much further than my hood. I made the drive straight through from Chicago arriving in Breckenridge at 8AM, so much of this driving was through the night. Kudos to the traction control, gross vehicle weight, and weight distribution for getting me there and back safely.
Most people will be fine with RWD unless they live in an area that receives consistent snow or have a very steep driveway. I enjoyed my driving and will be going back next year!