I thought I might resurrect this thread as it's one most people can contribute to; plus now I'm commuting I get to read a lot more.
I've just read 'The House at Riverton' by Kate Morton and loved it. I got it as a freebie at work and had never heard of it. I later found out it was a Richard and Judy Book Club pick, and am ashamed to say I probably wouldn't have bothered with it had I known. Lesson not to be a book snob learned! It seems to be a love it or hate it book - there were hundreds of 5 star reviews when I looked, but also a surprising amount of 1 star - but if you liked Downton Abbey I'd definitely recommend it.
I also enjoyed 'The Lighted Rooms' by Richard Mason recently. Both books are similar in that they're told largely from the point of view of an elderly woman, but I found it particularly interesting in 'The Lighted Rooms' that a 30-something man could capture the narrative voice of an 80-plus woman so well. It has an element of the supernatural in it too if you like that sort of thing.