I've actually only seen Howl's once, but I didn't like it. As seems to be the consensus, the animation was extremely beautiful and the score brilliant as usual, but it lacked in the story department. It was boring, slow, and a mess. I do think I should give it a another shot or two though.
I would have liked to see Hosoda's version though. Although I don't think he is too close to matching the brilliance of Miyazaki's peak years, I think I would give him the edge when comparing their more current works (i.e. The Girl Who Leapt Through Time and Summer Wars vs. Howl's Moving Castle and Ponyo).
Oh, and was the Porco Rosso sequel rumor ever dubunked? Or is it still floating around? Either way, it had the perfect ending, and a sequel would definitely ruin it.