You're talking right up my alley here! In SYWTBAI season nine as one of the last projects we had contestants pitch a Lost attraction.
@JokersWild ended up winning even though he'd never watched the show
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I agree there's a TON of opportunities for a theme park environment. The show has a built in mythology and awesome environment already in place. I always imagined the queue taking place in the Swan hatch complete with a button that'd have to be pushed every 108 seconds instead of minutes. The ride vehicles would be DHARMA buses and the ride experience would go through all the different iconic locations such as the Black Rock and the Barrocks, and end with a climatic encounter with Smokie.
On the subject of later season Lost, I actually love season five and consider it my second favorite season after two. Maybe that's just because I'm a time travel junkie, but I thought it was an ingenious device for us to see a lot of the island's history...plus season five gave us the EPIC Sawyer/Juliet love story (and I don't use "epic" and love story in the same sentence much...
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) I also thought the cliffhangers of that season were insane with the reveal of "Fake Locke" and the bomb going off.
Season six...yeaaaaa. It had some strong elements to it, most notably Terry O'Quinn as "Fake Locke". I love the way he played it mostly as a new character but inserted familiar elements of John Locke in just the right spots as if the real Locke was still inside him somewhere wanting to get out. My favorite season six moment is in the episode "The Substitute" where fake Locke yells at Sawyer Locke's iconic "DON'T TELL ME WHAT I CAN'T DO!"
That being said, the flash sideways should have NEVER existed and absolutely tainted the season. It would have been SOOOO much better if they'd spent more time fleshing out the backstories of the island, instead of trying to cram all the island history stuff into what I consider to be the absolute WORST episode of the series in "Beyond the Sea".
I still hold out hope for a Lost movie. I can totally envision a scenario where the remnants of DHARMA try to take back the island and Hurley and Ben have to recruit our familiar characters to save it. I can just picture a scenario where Sawyer's on a plane and he realizes he's going back to the island, and the camera pans in on a closeup of his face as he gives a dramatic "sonofab*tch!"