Only got to watch races in the 1960s and 1970s on TV... what little was shown. So can't help you there.
In the 1980s we still had Petty and Yarborough (for a while) but they were winding down their careers. Both had stayed too long and tarnished their careers.
In the 1990s we had the transition of drivers allowed to be characters to drivers having to be bland and politically correct.
Races between Petty, Yarborough and Pearson (while in their primes) tended to be strung-out train racing. Typically one or a few cars would hit the set-up and had the horsepower, so they lapped the field multiple times. Pearson was excellent on saving his equipment for the end and surprising people. When Petty was on (and he was often) he just ran away from everybody else. Yarborough was hard on equipment but if the car could stay under him and if conditions were tough (especially hot) he could lay it on 'em.
Kulwicki, Davey Allison, Rusty, Earnhardt, and Bill Elliott had some great battles - though Rusty and Bill petered out before Kulwicki and Davey really caught on. Earnhardt had some up and down years and was probably best during Rusty's and Bill's best years. You ought to watch some re-runs of those races. Some of them got over-hyped (like the so-called "pass in the grass"). But in this era about half the field were contenders to win, unlike years past where only a few were real contenders. We had more lead changes and passes within the field starting in this era, than in eras past.
From what I was told it was possible to meet and have meals with drivers if you lived in NC or SC where they lived. But by the 1980s that pretty much evaporated because TV coverage made it hard for drivers to enjoy "normal" life. Still, even today you can catch a driver on the streets or in a restaurant... particularly if you're in Charlotte. Where most people met NASCAR drivers was at local bullrings when some of them would show up to race the locals. Usually they were good about staying after the races and being friendly in the pits (especially Petty). Today that's quite rare.
The car exhaust noise changed over the years from lower-note big block rumbling to the higher-pitched whine of today's smaller but higher-revving engines. The biggest engine noise change occurred in the Busch Series when they ran V6s. Sounded like a swarm of hornets! Today's cars sound a little quieter (to me), possibly because they're engineered to waste less energy as noise. But that could also be blamed on my old ears too close to loud exhausts for too many years...
Up until the mid-1980s the car bodies looked a lot like street cars. Some race cars still used passenger car sheet metal (in some places). Then NASCAR allowed them to keep massaging the bodies until you weren't always sure what a car was supposed to be, so they started putting stickers on them to help you out. After too much complaining by auto manufacturers that the others were getting unfair advantages NASCAR took over and now we've got jellybeans that you can't tell apart if their stickers weren't there (although I admit that lately they've also configured the grilles to give us a hint too). But "win on Sunday, sell on Monday" pretty much had died out by the 1990s.
The 1960s through 1980s cars were boxy enough to allow sling-shot passes on the high speed tracks. Today cars can hook up in tandem due to aerodynamics. It's also a lot harder to see out of today's cars (as well as for fans to see the drivers in the cars as they go by). Although speeds are higher today, the cars have better suspensions and bodies too so they are less likely to fishtail around like the old cars. Both are a handful to drive, but drivers' approaches are different. The old guys could afford to trade paint more than today's guys can - in the old days a wrinkled fender was less likely to ruin your race than it is today. So driving was more brutish in the old days and more finesse today. (Not saying either is better or worse - just pointing out some differences.)
