Typically, AHRMA events are run at a very slow pace... so you don't have to pick one class, you'll have plenty of time between races. Also, they don't run a CCS type format at most venues. Saturday and Sunday both have the same classes and schedule... its like a twin sprint event, but slower between calls.
I really loved the atmosphere at the AHRMA event I did a couple of years ago. Laid back (and kinda disorganized) The best is watching some very overweight, very old men cramming themselves into leathers, then posting top speeds of 70mph down the straight at RA on some 1960's 125. I had an awesome experience.