Sight was not really something we got to enjoy. I remember tanking Ony in WoTLK and couldn't see anything. Just a blob since I was against the wall and Ony is so huge, it made my camera angle go hayware. I can also remember playing my priest in MC. Health bars everywhere, and of course all the dispels, so many dispels.

My friend was continually pissed because I didn't have individual frames for his pet using xperl, and therefore would never heal it. In general, I think it's not my responsibility, and blizzard seems to agree with giving pets better survivability over the years. But man, when his pet would die to aoe or something, he'd be like "DOOD, I CANT DO ALL MAH DAMAGE IF YOU KEEP LETTING MY PET DIE".

So keep your fucking mend pet up 100% of the time and move your pet out of bad shit, I'm healing 40/25/10/5 other idiots standing in shit they shouldn't be standing in. Not gonna add a bunch of pets to that list when you have a heal spell dedicated to them!

Just my own mix of addons really which i've been refining since i reset my UI in 2.0 (burning crusade launch) the main concept is focusing the most vital information on the center of the screen around my character without blocking my view, current main componentes are:

• dominos + omniCC + tulla range + inline auras, that gives me a nice action bar that displays a numeric timer for cd (center number), dot refresh timers (left bottom corner number), how many charges of an ability i have (right bottom corner number), active debuffs (yellow border around button), active buffs (green border around button), makes interrupt shine on interruptable abilies as well as shows a timer for the cast, etc...
• icehud for hud display, that's the hp/rage bars around the character, provides self and target unitframe as bars as well as target of target at the feet of my character (no visible since the boss isn't targeting anything)
• pitbull for raid and focus frames, it's customized to be very minimal, still want to make buffs i can cast display in a better way though to avoid the ugliness,
• raven for the debuff display to the right (the big debuff icons), this has proven to possibly be the best thing I've ever done, specially that now most stuff that requires tank attention is marked as a debuff on you.
• deadly boss mod timers show up to the right of the debuff bar, standard stuff but once again configured to only show relevant timers and stay out of the way.
• displaydock at the top with some libdatabroker plugins for gold, durability, quests, bags, performance and map amongst others and dominos minimenu on top in a way it makes it look like it's part of the bar (it actually isn't) this is done to replace fubar which actually allowed a plugin to have multiple buttons something libdatabroker displays don't these days
• MikScrollingBattleText with damage, events (and more recently healing) disabled so that it only shows me incoming damage, you could use blizzard stock ui for it but i find mik's more asteticly pleasing and informative with color coded damage, it's basicly my gtfo alert if i'm standing in fire or to see what ability is hitting like a truck
• bottom is just 3 chatter blocks that stay invisible if no chat is there, general / guild / party. this is mostly cause i'm super distracted and found this the best way not to miss what people are saying.
• minimap is just sexymap with minimalistic config
• tiddyplates, not shown but essential to tank and always active

That's about it more or less, i don't think my UI is perfect but it's been refined since classic with allot of time invested in spurs configuring each addon and I've grown pretty used to it.

For anything I didn't mention, the full addon list: http://pastebin.com/N207jztg