I've already welcomed you on another thread here at A2K, but I'll do it again here: Welcome & I do hope you enjoy yourself here!
I couldn't agree more on your thoughts on Lantana. When I first saw it (during the first weeks of it showing here in Oz) you could have heard a pin drop throughout the whole film. The audience (art house) was totally absorbed. I fully expected applause at the end!
Yes, a very subtle film. So much to think about after seeing it ... So much to discuss later. I saw it again, this time on video, a few months ago) & discovered much that I hadn't seen/ fully appreciated on the first viewing.
I see what you mean about the Altman influence ... The many threads, the way the characters' lives crossed, putting the bits & pieces together to form a satisfying whole.
What more can I say? It was truly one of the most satisfying films I've seen in recent years.