Denver is your best bet to fly into, which is on the NE side of the city. That said you don't want to be on the NE side of the city for a snow storm chase, so take the drive over to Boulder.
18z GFS is even more insane than 12z. Obviously that'll never happen but it's fun to watch. Then again those kind of totals are far into the danger zone for many people.
My biggest storm as an adult was in MD in 2010. We had two 20"+ storms within a week. It was nuts. The roof was creaking and I ran out of places to put the shoveled snow. It took a week to even get the neighborhood plowed so neighbors dug a path out to the main road.