Clean.
Apparently I’m too negative; who knew. There has been some rumbling in the world at large that I don’t provide an adequate number of UIs I think are “good”; instead of linking the newest Duke UI, I thought I’d post what I’ve been using for about a year now. I’ve made some minor modifications but the underlying premise is still the same.

Big Clean Version
Big Annotated Version
About the Screenshot
Let me take a minute to talk about the screenshot, since it’s far from the ordinary. I spent some time eliminating the background and some superfluous elements (chat, buffs, minimap) to draw attention to what I consider the ‘fundamentals’ of a healing UI – the unit-frames and their placement. Obviously there are certain “essential” elements that I’ve omitted (boss mods, action bars and buffs namely), but I find their placement to be largely dependent upon the placement of the unit-frames.
Meta Placement
The placement of the unitframes is done for one reason: to minimize the space I need to check to access crucial information. Since this is a healing-focused UI, I am looking at my unit-frames most of the time, with the rest of my time looking for environmental cues which tell me I should move (namely: fire). The placement of the unit-frames slightly below my character let me see ground effects on my character as well as moving doomfire-like effects with ample time to get out the way. I’ve found this specific setup highly beneficial, especially on fights like Razorscale, Mimiron, or Hodir which require constant “ground-effect-checks.”
Colors
Before discussing the unit frames themselves, I thought I’d take a minute to discuss my color choices. I utilize class colors to eliminate the need for class text, and visual prioritization of my healing targets. I’ve changed most of the class colors from pastels to neon colors simply to make them stand out against the relatively pastel background found in most raiding environments. Thanks Hal! I also use color to differentiate between certain elements without the need for text; for example the two status bars under the focus frame.
Unit Frames
These frames are probably middle of the road in terms of size, they’re large enough that I can see them without searching and small enough that they don’t block my field of vision. I’ve chosen to display only “essential” information on each frame. The player frame displays my mana and health only, while my target frame displays the name and health of my target. Only the auras displayed in this area are player debuffs and target buffs (cast by me only); relevant target debuffs are replicated on Grid and player buffs are not typically “need to know”.
The target of target frame isn’t really a frame at all; rather it’s a dogtag anchored to the target frame. This is done for two reasons: first, I don’t think ToT information needs its own bar. The name gives me enough information, and if the target is a non-player it will also display a health percentage. This is done to check up on percentage based boss cues if the boss is not selected. I honestly believe that a ToT frame with a health bar is the best indicator of someone who hasn’t thought about their UI very much, or someone who designs it for the wrong reasons.
The focus bar is used primarily to help me keep track of who my focus is, but also serves as a nice reminder of focus health when checking on the status of the two short-term holy paladin buffs (Beacon and Shield) both tracked by status bars under the focus frame. By keeping a physical bar at that location, I don’t risk missing a heal on the tank by having to look at a random location on the screen. Since I use focus macros for tank healing and buffing, the separate focus frame allows me to use my target frame as a second functional focus frame for an off-tank, obviously achieved by zero-target switch click healing.
Cast Bars
Though not visible, the cast bars appear under both the target and player frames. Each contains spell name only as well as remaining cast time. The cast bars have the same aesthetic as the unit-frames, though they have a slightly different texture to differentiate them on the fly.
Defense of Visitor
The most common complain I read about any of my UIs is that Visitor sucks; quite frankly, every single one of you can blow me. You all have terrible taste, and I mean that sincerely.