I like
@mellored's suggestion to make healing to be temporary hit points.
At my table, we're focused more on potions than spells, though.
One thing I've done in my campaign: healing potions always heal the maximum amount possible, but they cost 50% more. It's just a little thing--more reliable potions--but it makes a big difference on the battlefield.
We're testing another house rule at the moment, too. If you drink a potion as a Bonus Action, it heals the minimum amount possible. The theory being that in your haste to open and consume the potion, you end up spilling most of it.