I agree with your assessment of the Palmers. I have been of the opinion for awhile now that they are okay with each other. They have each found their own way of adapting to each other's quirks/idosyncrasies/impolite behavior. It's true that Mr. Palmer has discovered that Charlotte is not a great intellect beneath her beauty. However, unlike Mr. Bennet who became resentful to the point of purposefully heckling and teasing his wife in a similar situation, Mr. Palmer seems to have taken an 'oh-well' attitude and somehow between the two of them they have manganaged, in their own weird way, to make their marriage work for themselves IMO.

As to Elinor's insight into the Palmers---I felt too that she did it with very little time but then I decided that she probably followed something along your line of thinking about the Palmers as a couple, and added with her, apparently good instinct about people, was able to come up with her conclusion about Mr. Palmer. Also, literally being there, she may have had some clues through body language, what his eyes 'said' as opposed to what his words said as well as words and actions beyond what we see and hear. We aren't privy to what exactly she uses to base her decision on, that allows her to make the determination she does about Mr. Palmer. She may not even be perfectly right but she senses, through what she has observed, that there is more to him than immediately meets the eye. Great post. Thanks.