Just wanted to throw some of these Ideas out there. feel free to add on if you like.
1.Food gives slight sp regen,more for things like water and chocolate and less for rotten foods etc.
2.Pets,feed them to keep them alive.Do something like defend or come with you.Should be a rare find.
3.Thirst to go with hunger.Replenished with liquids.
4.Lootable vending machines.
5.More accessible buildings.
6.Large shovel easier to find.
7.Drivable vehicles,rare and decrease sp taken to travel and used to store items if needed.Keep in safehouse garages and require gastanks to operate.
Post your ideas below,maybe they will see and some will get implemented.