I need to come up with a plan for visiting the 35 other Colorado airports I plan to visit (I left out DIA, Greeley-Weld since I've already been there, and Centennial which is my home airport), as well as one airport in each of the six states I want to visit. I picked up this neat booklet for free from my flying club that contains detailed information on all of the publicly accessible Colorado airports, which includes an overall map. Looking at the map it is easy to see that I can achieve my goal with four flights.
The Northwest flight includes airports north of Centennial within a short distance of I-25. This flight extends up into Wyoming, where it makes sense to land at Wyoming Regional airport.
The Northeast flight includes all of other airports north or Centennial from Ft. Morgan east. This flight will also fly into Nebraska, where I can land at a number of different airports.
The Southwest flight goes south of Centennial mostly along I-25. I thought about extending this down into New Mexico, but I found a better way to do this by including New Mexico in the Southeast flight.
The Southeast flight consists of the airports south of I-70 that are farther east of I-25. This flight will go into Kansas, Oklahoma, Texas, and New Mexico. It is by far the longest flight because the airports are the furthest from Centennial and covers the most area. It is possible to split this flight up if necessary but it isn't practical because it takes so long just to get into the area. Including New Mexico in this flight actually reduces the southwest flight by 80 miles while only adding 50 miles to the southeast flight. It also eliminates the hassle of having to fly over the Raton mountain pass, which might otherwise require a checkout in mountain flying.
These flights are going to be major tests of my flying, navigation, communication, and planning abilities. The GPS I got for Christmas is going to reduce a significant amount of planning and navigation hassle. In the event that the GPS fails I feel confident in my ability to get safely back to Centennial through normal VFR navigation, though it will probably mean stopping the flight early. The length of the flights, especially the southeast one, are going to require me to keep an eye out for optimal flying days. The actual flight time of the longest flight is over five hours, but considering all of the time at airports, it's really going to be an all-day affair. So I need to choose days with a lot of daylight hours, and a very low chance of afternoon thunderstorms. But I look forward to the challenge. It's going to take a lot of commitment of time and money, but the benefits will be a great deal of experience, a lot of cross-country flight hours, and a bunch of fun!