IMO, the Summer of 1970 was the most wretched sequence ever on DS. All the characters ran around twiddling their thumbs, behaving like they'd been lobotomized, and doing everything possible to avoid communicating with one another about what was happening. It was so painful the first time around that I vowed never to watch it again, and I haven't.
Adam & Eve was another story line that I thought dragged and dragged endlessly. I wasn't fond of the Dream Curse either, but I did watch both all the way through twice as they aired on the Sci-Fi Channel. Since then, however, I only watch selected episodes featuring Prof. Stokes or Nicholas Blair, the only redeeming features in either sequence.
My favorite story lines to rewatch are 1995, 1795, early 1897, and the 1967 Laura plot. While 1970 PT, 1841 PT, and Leviathans don't rank high on my list of favorites, I don't have a problem seeing them again, though I agree that certain parts are more interesting than others.
ProfStokes