I've run a trinity setup of Prot Pally, 3x Frost DK and a MW Monk for this expansion in dungeons and I've had pretty decent success with it doing some "OK" level mythic+ with relative ease. I've been too lazy and/or busy to really push high ones.

I think a lot of these kinds of things are really down to preference in playstyle, apart from encounters that require specific things out of your team. Personally I usually drop my healer off to the side somewhere to free cast healing and only move it if I need to. I have a separate mapped key to make only my DPS toons follow my lead, so I often move those separate from the healer. Additionally I also have WASD+Ctrl/Alt/Shift modifiers setup for moving different action target groups out of harms way. And as a lot of people do with melee, I have IWT in my rotation so it just gets spammed. I do have a key for a mapped key step state action that toggles the "auto-iwt" on and off in my rotations as well so I can turn it off if I want to.

Frost DK is fairly simplistic so it's easy enough to macro and there is only one proc that I really have to worry about, which I chose to do using a custom, invisible menu. Pally is pretty much a case of "if it's available, press it" as far as attack spells, so it takes no real baby sitting.

Healing I handle with a combination of the pro-config, virtualization actions that change my healers rotation, essentially toggling it in to different "healing modes", and click healing through a repeater region. All my heals are also set up as 2-tier macros with the first line being the same heal with a [target=focus,help] conditional. This way I can set focus on a toon (through the repeater region) and my healer will just heal the focus target as long as it exists. Naturally I have a key for dropping focus as well.