How do you like the TV? What did you have before it? I've wanted to get some more user feedback of the quality of that TV, especially with normal TV viewing. I have a client with a plasma that is looking for something different/larger and I'm leaning towards the 85" 900 model.
For audio, I don't get much involved with it as I think opinions are all over the place. A good A/V receiver has good amplification in it. A good set of separates won't necessarily sound better, but will offer future growth and a good amp is typically a good amp for years and decades to come. I've never craved more power than what my current receiver puts out, so I don't think much about it.
I do think that if your room can support it, adding speakers for Atmos may be a good way to go. Especially if you are a movie buff.