A bit of detail on the Cherokee 6/ Saratoga family of aircraft;
An early C6 300 (like G-PECK, which I used to own) has a useful load of 1,400lbs. So, six 180lb adults = 1,080lbs, with 380lbs left for fuel and bags. 4hrs plus vfr reserves. A real six seater.
An early Saratoga (like G-GIPC which I currently own) has a useful load of 1,300lbs. So six adults with 280lbs left over for bags and fuel. 3hrs endurance, plus vfr reserves. Not quite as good, but still an 'honest' six-seater.
Then you get to late Saratoga's, fully laden with kit, and the sums start to fall apart, as you're down at a useful load of 1,100lbs, so you either need to be flying to the field next-door, or carrying super-models!