[DonC]

Bob:
Whether you trailer or drive is up to you. I trailer because I prefer to make the trip to Denver in two days (about 600 miles a day) and I don't have to plan around weather. I've done the Denver run in 3 days in my Cobra without any ill effects other than running in steady rain the last 2 hours.
I'm accustomed to fairly "hard" pushes in the Cobra (PDX to SFO, PDX to SAC in 1 shot) and it doesn't bother me but those kinds of distances can be tiring if you aren't used to them.
I just find it less tiring when I'm making long hauls to trailer the Cobra and I'm fresher when I arrive. Your results may vary. The Mile Hi club makes arrangements for trailer parking for participants in Denver.
However you get there, it's a heck of a fun run.
DonC