I am finding that while I generally do prefer to read books in printed hard copy (and trade paperback more than hard cover), some books do lend themselves to reading on-line. While I haven't attempted to read Trollope or Dickens as an electronic book, Samuel Butler's The Way of All Flesh is going reasonably well, and I read snatches here and there, particularly while waiting on downloads (as my internet connection is still pretty iffy these days).
At any rate, I am not going to make reading Henry James a particularly high priority, but after I finish The Way of All Flesh, I will see if reading Henry James on-line goes as smoothly, or if I find I have to devote longer periods of time and more uninterrupted reading to make any progress. If it is the former, then I will try to tackle these novels (and a novella or two) in order of their publication:
The Portrait of A Lady
The Princess Casamassima ??
What Maisie Knew/The Turn of the Screw
The Awkward Age ?
The Wings of the Dove
The Golden Bowl
This is certainly the core of his work, though it is not a complete list of his novels. The only James I have read to date is The Ambassadors, and that was in undergrad, so I don't really remember much about it. All of these works, with the exception of The Princess Casamassima can be found at Project Gutenberg. I suspect since they are in the public domain, you can find them fairly cheaply for the Kindle at Amazon, but I'd rather download them from Gutenberg, since the proof reading and error checking for PD works seems somewhat better. It is totally hit or miss with older works at Amazon, though new books are generally fine. Incidentally, it is an Australian site that hosts Princess Casamassima. If I feel I am simply running out of time (with reading in general) or getting bored with James, I would probably cut it back to Washington Square, The Portrait of a Lady, The Bostonians and The Wings of the Dove.
William Dean Howells has definitely fallen from fashion. At one point he was read as much or perhaps more than Henry James (they were mutual admirers, incidentally). Curiously, the Library of America (or rather John Updike) makes a reasonably strong case for reading Indian Summer,* which is essentially forgotten now, but they did not publish A Hazard of New Fortunes (which can be found at Amazon, as well as at Project Gutenberg). As it happens, I do have A Hazard of New Fortunes in paperback, and that is probably how I would actually read it, though I don't even have it on my reading list at the moment. I'm not sure I will ever tackle Indian Summer, but I do plan on reading The Rise of Silas Lapham, and in this case, I would see if I could make reasonable progress with the epub file before I tackle New Fortunes, which was published a few years after Silas Lapham. As worthy as Howells surely is, I just don't see myself making a thorough study of his novels, outside the two or three that I have listed.
* Updike also suggests that A Modern Instance is worth reading. Most curiously, NYRB has published their own edition of Indian Summer (the only novel by Howells that they publish), which does suggest it is a bit of a forgotten gem. Of the two editions, I'd still go for LOA in this case, as the Updike introduction is of more interest.