While I would totally agree with you regarding the black Hills area, especially if you fly into Rapid City rather than Denver, the Grand Canyon/Mighty Five area also has proximity to both Phoenix and Las Vegas, either of which could serve as your flight terminus. Those two cities offer tons of things to see and do other than hike through scenic beauty. Las Vegas in particular would provide plenty of night life and entertainment opportunities while still leaving at least a couple of the mighty Five within day trip range. The Grand Canyon would also fall just within day trip range although that might be a bit of a stretch. If you did the later, you could also include either
Red Rock Canyon National Conservation Area,
Death Valley National Park or both. Eight days days of using Las Vegas as your vacation hub would allow you to mix and match natural scenery (and short walks) with man-made wonders.
AZbuck