I'll admit to having 'issues' with the new behaviors and tactics. I came across a post on gamefaqs - full credit to the author there 'themasterllwork' - I followed his advice and I have to say that I am having way more fun and now my party is doing 'sort of' what I expect rather than all running around at random:
Global Settings
Potion Keep: 2
Use Potion at: 30% HP
Me Follow (Me), Reserve: 30% Stamina, Priority: Whirlwind, Grapple
Cass Follow (Cass), Reserve: 50% Stamina, Priority: Warcry, Bodyguard
Varric Defend (Me), Reserve: 30% Stamina, Priority: Poison Weapon, Full Draw
Solas Defend (Cass), Reserve 50% Mana, Priority: Barrier, Revive
My toon is a dual wield rogue so I adjusted my skill Priority accordingly. There is another great post in the same thread about setting mages to use no potions which has helped a ton.