We've travelled from southern Kentucky to Yellowstone a number of times. We leave at dawn and I drive until I get tired then usually pick a nice truck stop to catch some zzzz's. It's not unuaual for me to drive 600 miles before taking a long break. We've also been to Orlando and Disney a few times and I have driven from Disney back to Kentucky only stopping to refuel; a distance of about 750 miles. It just depends on how quickly you want to reach your destination but don't let your excitement overide your need for proper break stops. To give you actual numbers ideally I'd take 3 days to drive from your location to Yellowstone with the same number to drive home. This should leave about 12 days to tour Yellowstone which can be done. We choose a section to visit daily and have seen or done about everything Yellowstone offers except for hiking the back country. There's enough to do in Y'stone to spend your whole vacation there but you can also drive down to the Tetons and Jackson Hole fairly easily depending on where you stay in Yellowstone.