Im going to keep the patch changes in mind where we will return to 100% raid healing. 22-24k mana is ideal and around 275-300mp5 should be plenty with replenishment.
My overall consensus for every encounter is haste haste haste haste. Haste lessens the need for spamming chain heals. Lets you choose your heals wisely and allows for mana regen in between casts. Currently there are really only 4 fights that are a remote challenge for a healer so ill comment on those.

Patchwerk
24k mana over a 3minute fight is enough if you have replenishment. Currently spamming CH that entire fight with 717 haste and literally go oom the last heal before he dies.

KT
Not hard but in terms of gear you want to get your crit nice and high. CH is useless except for the occasional heal on melee or ppl chaining frost blasts. Its a lhw fight only and if ur on the raid you should only be doing this and riptide of course.

Malygos
Focus Target frame is your friend. Again haste haste haste. You should just spam your chain heals on the focus target frame and when he changes target find that target on ur grid/raid frames and throw a chain heal their way. The chain heal should land rght after that person gets hit and you will get very little overheal and extreme effectiveness. 2 sec chain heal is all you need once you've obtained that haste wear some more regen. Theres time to regen while your vortex'd and the 2nd phase is more of a spot heal/reaction heal game again allowing regen. Save your mana tide for the 2nd phase as its a good chance your healers will need the mana then.

Sarth 3 drakes
Go for haste to get quick heals off. With the bursty nature of the damage in this fight you'll want as much as possible. Favor single target healing on the raid and chain heals on the elemental/drake tanks to help out melee. If you're not on the drake tank you should be able to position urself near the main tank. Throw riptides/lhw their way and its also great for moving left or to the middle for lava waves.
Its not a massive raid damage fight when executed correctly and if your planning on getting sarth down with 3 drakes you shouldn't have to do a huge amount of healing. Mana is very rarely and issue and you will have time for 2 mana tides so get your first one down quickly (around the first or second drake)

Thanks for the input from everyone so far. It looks like conventional wisdom is saying that Chain Heal throughput is best for Drakes and Malygos. There have been caveats about having a certain level of mana, etc, but I think that's probably one of those situations where you're geared enough for the fight or you're not. I'll be editing the original post to include those two fights.

As always this is still up for discussion and I encourage anyone to correct flaws/omissions to make this better.

Having done everything but 3drakes atm, I just have 2 regen trinkets and 2 output trinkets. Switch between them depending on fight and keep the rest of my gear fairly balanced. I'm pretty all over the place with heals on most encounters though, switching from rip/lhw to chain heals and healing whomever unless it is 3drake tries. Post patch I'd probably just go with a haste+mp5 set since we will probably become much more raid-healing centric.

Are we talking about 25-man 3 drake sartharion or 10-man, because I see a HUGE gear change between the two. With 25-man, gear for haste for raid healing sure. 10-man basically means 2 healers: one on the sarth tank and one on the drake tank splitting everything else. At that point (imho) you want to gear for single target healing (crit and spellpower) to keep the welp/sarth tank alive. Raid healing is a bit of an afterthought and something you have to split with the other healer while you have time if that makes sense.

I fully agree with prevoius post.

I my opinion, resto shaman has two basic gears: throughput and longivity. You should wear throughput all the times except the ones when you goes OOM, where you should wear longevity