I do wish Ana Lucia had lasted longer, they never really found another believably tough, take-no-shit female character once her and Rousseau are gone. Again my memory of what happens in each season fails me, so I'm never entirely sure whether I'm spoiling you on anything, but the general inert status quo and constant reset-buttoning of the show means it's pretty much unspoilable outside of certain details.
I admit i never would have guessed you'd be as enamored as you are of Sawyer.
Then, the earlier season are definitely his peak, before his schtick becomes a bit more humanized and watered-down. I also wonder how much of his appeal is as a contrast to Jack (which is also something Locke benefits from). The very best character/performance of this show is still to come, though
Mr. Ekko is pretty much a complete waste of what could've been a cool character and also hands down possibly the dumbest death on the entire show. Why they thought the smoke monster growing hands and bashing somebody against trees would be anything but hilariously awful is anyone's guess.
You're aware of "WAAAAAAAALT! WAAAAAALT!" being a meme back in those days, right? Losing Harold Perrineau was one of this show's best decisions, what a one-dimensional character. The kid actor who played Walt also went through a hell of a growth spurt after season one, so they had to cover it up by having his subsequent scenes take place in the "future" or whatever.
I still think of Twin Peaks as essentially an all-time fantastic pilot, followed by.... whatever the hell else the show was. Come to think of it, that's basically what Mulholland Dr was as well.
I also admit that even after your description of the season 2 finale, I'm still not sure I remember it.