Healing. I just really like the 4e healing surges and none of the kids is playing a cleric, so gone are HD healing. Now each PC gets 8 healing surges that are 1/4 of hp (min 5) and they can spend as many of they want during a short rest. A long rest restores all hp and surges (I will probably require a few days rest for a long rest). Also, the fighter's second wind allows them to use a surge as a bonus action.
This may or may not be a permanent house rule but it should work for now.
This may or may not be a permanent house rule but it should work for now.