I thought driving the Countach, Testarossa, Corvette and Firebirds in Grand Theft Auto: Vice City while listening to '80s tunes was fun, but then it became boring after a while.
Vigilante 8 was pretty good back in the day.
But the one I thought was most fun was Mario Kart 64, probably because it wasn't just one player and competing against another actual person was most of the fun.