NASA conducts high-altitude tests out of COS all the time. There is always a NASA plane sitting at COS, usually a 757 but they also bring there 777 to COS.
Pretty much any aircraft ever built with landing gears can take-off and land at COS. Some aircraft (most actually) will have some restrictions but they will be able to land and take-off.
COS currently has the longest runway in Colorado, 13,500ft long. The runway is also 200ft. wide.
Don't forget that COS shares its runways with Peterson Air Force Base which recieves all sorts of military aircraft from F-15s to C-5 Galaxys. Mainly C-130s though.
"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran