mds0927, just curious: what time of year will you be traveling? It could make a bit of a difference for the CT.
Why is CT such a hotspot, in your opinions? I've seen the photos of
each of the villages, which are quite beautiful, but other than
hiking/sightseeing, what is the big draw?
One big reason is sheer proximity to a major cruise port (La Spezia). It's within very short range of that port thus a no-brainer for ship's tours. That's a big reason why it's become so overrun during the day. A recent expansion of that port means huge ships unloading thousands of passengers at a time, and the tiny villages weren't built to handle those sorts of numbers, especially when adding in the numbers of tourists who are staying in the accommodations or day-tripping for Florence/other locations in the region.
Yes, it's very pretty/extremely photogenic: the millions of appealing photos out there on the net are compelling. It's also fast and easy to travel between all 5 villages as it's only 7 miles from one end to the other.
Rick Steves elevated awareness of this area years ago when it wasn't yet a hot destination. His guide books and TV shows have contributed to the mass...although in fairness, I think many of the readers come to spend a few days rather than do it as a day trip: the best way to 'do' the CT.