I have been there two times. 2002 --2007. The first time was ok..lots of cool bikes to look at...I am not a Harley guy but rather a triumph rider... I guess I don't fit the advrage rally type...we were going to spend 5 days there...I was done in 2 ..Ben there done that..
The ride there and back was the real highlight tho...left from the west coast ...all back roads..2002 was the best trip really..I was on a then bran new triumph bonnivlle America..it got a ton of attention from rally goers ..I would come out of a gas station there were hundreds of Harley's. Some extremely customized ..my little triumph had a crowd of bikers looking at it...I met and visited with some real interesting people...
I recall a guy pulled up on an old beater Electra glide...that bike looked like he lived on it...which he actually kinda did..he was from Bay Area and left the 4 th of July and spending all summer riding...he had over 200 k on that thing...
On other guy I ran across was on an old r80 Bmw...actually turned out to be a collage kid...he was like 6-4 230...he looked pretty funny on that bike...he was from Michigan I believe..it was his dad's bike..it had been in the garage not run for over 20 years...he cleaned the carbs put in a battrie and plugs and lit out for California...I rode along with him all the next day through Wyoming ...
My advice for surges is allow plenty of time for back roads you don't meet too many people on interstates..