Over about 4 months in 1985, Patrick Renworth and Mike Whitehurst did the then-standard 54 Colorado 14ers as a thru-hike, meaning they walked between all the peaks. The pair covered about 1600 miles hiking from Pikes Peak to Longs Peak. A recent article on referencing this trip is here. The Colorado 14ers were again thru-hiked over about 72 days during July-September 2013 by Junaid Dawud and Luke DeMuth. They did classic thru-hiker style - no car rides for the full 1300 mile trip - and tagged all 55 (now) "traditional" 14ers, plus 3 additional high points over 14,000'. A map of their route is here. The Denver Post had an informative story on their trip (published just before they completed the journey). There was a lengthy tread following their trip on 14ers.com (now gone?). Star backpacker Andy Skurka called the trip "The Coolest Thru-hike of the Year", and posted an interview with the pair on his blog.
Some of the 23-page 14ers.com thread is archived on these pages: