"I hope," said he presently, "I have not been severe upon poor Mrs. Churchill. If she is ill I should be sorry to do her injustice; but there are some traits in her character which make it difficult for me to speak of her with the forbearance I could wish. (Chapter 36)

The double monologues are very funny—I agree with you both that neither Mrs. Elton or Mr. Weston is really interested in the other or what they have to say. Even though they are not interested in each other I think there is some intriguing information given in their monologues. Mr. Weston is a bit biased of Mrs. Churchill, I don’t blame him but he does offer the possibility she might really be ill. Like Mr. Weston, I also wonder at the inconsistency of Mrs. Churchill being too weak to get to her conservatory and a subsequent desire to travel so quickly to London:

"The evil of the distance from Enscombe," said Mr. Weston, "is, that Mrs. Churchill, as we understand, has not been able to leave the sopha for a week together. In Frank's last letter she complained, he said, of being too weak to get into her conservatory without having both his arm and his uncle's! This, you know, speaks a great degree of weakness -- but now she is so impatient to be in town, that she means to sleep only two nights on the road. -- so Frank writes word. Certainly, delicate ladies have very extraordinary constitutions, Mrs. Elton. You must grant me that." (Chapter 36)

If Mrs. Churchill is not really ill but uses her health to control people around her then the inconsistency is explained and Mr. Weston’s incredulity at her recent weakness and wanting to make a 190 mile journey with only two nights on the road is valid. If Mrs. Churchill has really been ill then there is a real mystery because I think a bumpy and fast carriage ride will be very unpleasant for a woman in pain. However, I think there could be third explanation for the speed of their journey—perhaps it is Frank that wants to travel so fast. In Chapter 27 Frank may have persuaded the agreeable Mrs. Weston that she promised to visit the Bates to hear the new pianoforte the day after the Cole’s party when maybe it was Frank who wanted to pay them a call and hear it himself. So perhaps Frank uses the cover of a woman to move about by design again and it is Frank who wants to return to London and hence Highbury as quick as he can? In Chapter 26 Frank “owned that he believed (excepting one or two points) he could with time persuade her [Mrs. Churchill] to any thing” and one of those points his being allowed to go abroad.

Mr. Churchill has pride; but his pride is nothing to his wife's: his is a quiet, indolent, gentleman-like sort of pride that would harm nobody, and only make himself a little helpless and tiresome; but her pride is arrogance and insolence! And what inclines one less to bear, she has no fair pretence of family or blood. She was nobody when he married her, barely the daughter of a gentleman; but ever since her being turned into a Churchill she has out-Churchill'd them all in high and mighty claims: but in herself, I assure you, she is an upstart." (Chapter 36)

Mr. Weston’s thoughts on Mrs. Churchill “the lady” was amusing but also seemed to describe a less wealthy Mrs. Elton (perhaps also her sister Selena) who I think was barely the daughter of a gentleman before marriage and is doing a fair job of regaling everyone with her own high and mighty claims. Also the Eltons seem to have different views of their courtship, Mr. Elton’s:

…he had gained a woman of ten thousand pounds, or thereabouts; and he had gained her with such delightful rapidity -- the first hour of introduction had been so very soon followed by distinguishing notice; the history which he had to give Mrs. Cole of the rise and progress of the affair was so glorious -- the steps so quick, from the accidental rencontre, to the dinner at Mr. Green's, and the party at Mrs. Brown's -- smiles and blushes rising in importance -- with consciousness and agitation richly scattered -- the lady had been so easily impressed -- so sweetly disposed -- had in short, to use a most intelligible phrase, been so very ready to have him, that vanity and prudence were equally contented. (Chapter 22)

Then Mrs. Elton’s description:

"Very true, Mr. Weston, perfectly true. It is just what I used to say to a certain gentleman in company in the days of courtship, when, because things did not go quite right, did not proceed with all the rapidity which suited his feelings, he was apt to be in despair, and exclaim that he was sure at this rate it would be May before Hymen's saffron robe would be put on for us! Oh! the pains I have been at to dispel those gloomy ideas and give him cheerfuller views! The carriage -- we had disappointments about the carriage; -- one morning, I remember, he came to me quite in despair."

She was stopped by a slight fit of coughing, and Mr. Weston instantly seized the opportunity of going on. (Chapter 36)