Once every few years I like to go up to Loudon in June to watch the crazy guys go round the track. A few years back I went with my son and he got drafted to help in the pits to help a couple pro guys riding in a Supersport race. He was wearing long pants so he could cross the wall. Those guys would pass the amateurs like they were standing still.
The Saturday before the big race at Loudon is a lot more relaxed. You can walk around a talk to all the racers. You drive right in and park in the infield. Walk through all the garages and wonder wherever you want. As long as you don't cross over the wall.
One of the track day orgs has a Road America weekend either the weekend before or after the motoamerica races, and some of the riders will be there testing their setups.
It's a humbling experience being out there, riding at 95% of your ability, and getting passed on the outside by a kid half your age on a bike with half the displacement.