I rode the NSC (100) and enjoyed it tremendously, but I was pretty sore afterward. I was OK for 80 mi or so, but the final bumps became rather annoying and couldn't imagine a long ride the next day. Some beers, Alleve, and stretching left me still sore on Monday, but I'm in good shape today. I averaged about 16.5 mph doing most of the work myself after 45 mi.
Anyway, I want to do RAGBRAI in 2008 but wonder how it's possible to ride similar distances on consecutive days. Does a more casual pace make each day much easier on the body? I hear that lots of non-hardcore people ride RAGBRIA, so it must be less intense than a series of NSC-like rides. I even saw a guy on the NSC who looked vaguely like Jerry Garcia and who said he's ridden RAGBRAI 3x.
FWIW, I'm 45, ride 50-100 mi/wk, and ride a custom Ti bike. I don't anticipate finding more training time. My previous, longest back-to-back on conseq days was a 60 mi followed by 45 mi just last week; that wasn't too bad.