I have already discussed healing in Ulduar and what we need to change from our Naxx routines in two previous articles:
Ulduar Paladin Healing Guides
Ulduar Paladin Healing Tips
After a few raiding nights, and advancing a little more in Ulduar myself (up to Thorim), I'll try to update my views. You can probably expect a "trash healing guide" I'll write during the weekend, as I find sometimes trash more surprising than bosses :P
I've said earlier to use Beacon of Light on yourself. That's still very valid for most bosses I've seen. On Ignis, Razorscale, XT, Kologarn surely, on other bosses (Iron Council, Auriaya) that is more of a discussion and that can depend on your assignment.
Now I've really seen trashs where Beacon should be on you or not, these are the trash mobs before Kologarn (antechamber) and before Auriaya.
When you pass XT, you'll be in front of packs of 3 sorts of mobs, sheep and ban can really help you a lot but expect to take some damage spikes on you (there are chain lightnings), while if your raid does good cc, and if your tank for the giants don't stand on charged punches, there should be only one tank (2 in heroic) tanks taking damage. This is a perfect time to use Beacon on you to ensure your survavibility while keeping a constant focus on your tank for reactivity on damage spikes.
Once you've down Kologarn, you're going to face the iron giants duos on Auriaya ring. These guys can output huge damage spikes on your tanks, while the rest of the raid should take very minor damage. That's the perfect set to have your beacon on the tank that you're not healing (they require a tank on heal infusion on each of them). That will allow you to heal both of the tanks at the same time, and help a lot with these bad and dealy damage spikes while your raid takes care of the lightning orbs and giants.
Clearly, these two settings are very different, and that's what I like the most in Ulduar. Bosses, but even trash mobs have very different strategies, require cc, require different healer assignments ...etc
Adaptability is a real raiding strength and knowledge, something you don't just get with loot. That is what I like in raids that push you to play a little better than just heal/damage spams.
I surely wish to see more of Ulduar soon, the deeper I go, the better it becomes. Please don't nerf the third part of it too soon, Blizzard :P