Well, another day and another boss, though I have not yet gotten her down. Vicar Amelia is the first really "important person" boss, and I know she's a big transition one, as she sets the time of day from evening to night.
The most frustrating thing is that my last attempt, which forced me to set down the controller and take a break, I had her to within 10% of defeat. After many attempts in which I was basically getting two or three hits in, I really thought I'd figured out the boss. I think I may have gotten greedy though. Unlike Cleric Beast or Blood-Starved Beast, you can't just stay right in Amelia's face, as she's got a ton of close-range attacks that are very hard to dodge.
So far, my most effective strategy has been to stay at mid-range, baiting some of her long-duration attacks (there's one ground-pound she does that has a shockwave effect and must be dodged even at range) and then closing in to slash at her legs.
I did also manage to stun her at one point, and got a nice nasty visceral attack on her face.
I knew she could heal, but maybe she sensed I had my Numbing Mist on me, because she never chose to do that.
Between attempts on Amelia, I allowed a Snatcher to kidnap me and freed Arianna and took my first sort of accidental attempt at Darkbeast Paarl. Having Henrik's gear allowed me to survive a bit longer against him than I expected, but I think Amelia's really the next boss for me to down.
Still, knowing that seeing Paarl would (for some reason) allow me to have a friendly interaction with Djura, I went and talked to him and then Bold Hunter's Mark'd out of there, basically figuring I never have to go to Old Yharnam again (except to kill my new buddy and steal his clothes.)
I think that post-Amelia I'll be in the right area to start the DLC content if I choose to get it. I think taking down Paarl next wouldn't be too crazy, though I might instead go do Hemwick (I don't know about the level that leads to the boss, but I'm given to understand that the Witch is very easy. I might even spend all my Insight at the shop to make sure there are very few adds.)