I wouldn't mind a longer LM race; say 2 hours. Or, maybe a 4 hour race, with optional driver changes (maybe the people who run the whole race by themselves get some sort of a bonus... :shrug
Maybe even one 6- or 12-hour race during the season as a real endurance race.
S2L is fun, though; lots of cars can equal lots of crashes (I got spun in the second turn of Sunday's race), but it's nice having lots of people to race against.