(The real Paul Mags this time…goofy humor and all. :D)
Why the CT?
After doing the CDT, I can say there is extreme pleasure in following a well marked and maintained trail.
The CDT was perhaps the most rewarding trail I’ve ever done. Remote, raw and wild. But also mentally exhausting at times.
Sometimes you just want to walk, look at the scenery and not have to make major navigational decisions. Let the mind go on auto pilot (I still suggest bringing maps to do the CT though, esp if you want to take side trips (14ers) and/or alternate routes)
The CT takes in some of the highlights of the CDT (they share the same trail for ~200 miles), but without the constant navigation issues. And, if your significant other is new to LD hiking, it is a great trail to introduce someone to thru-hiking. The first ~100 miles from Denver offers options for relatively frequent town stops and lower elevation and easy terrain.
As Garlic suggested, I have an “end to enders” guide on my website.
In short, the CT is a great long-vacation hike. The CDT was a wonderful journey.
Both trails have their niches and joys.
Frankly, I am glad I did both. 
Paul Mags