Now look, what's all this about book groups shouldn't read Middlemarch? Of course they should. I presume it's because Middlemarch is considered too long. The point is that book groups will become slaves of what fits the month long reading period, if they're not careful, instead of enabling their readers to discover great, inspirational literature. What's the purpose of a book group if not to offer an eclectic choice of reading?
The sad and terrible truth is that we only have room in our lives for a very limited number of reading experiences. For heaven's sake, read the very best. Don't be limited by length.