Yeah, I'm definitely looking forward to collecting anything leafy, acorny, or mushroomy, and to seeing a notable seasonal shift (spring into summer wasn't a very big change in appearance.) Fall is definitely the most glorious season, where I live (Eastern Ontario), even if what I prefer to DO/how I like to live is most available in summer. I don't like summer itself that much...I just love the activities I can do most effectively then, like cycling and gardening. I'm indifferent to Halloween, but I love harvest themes and anything
woodland.
Those are things I love and lean toward collecting
irl, too, so of course.

I'm gonna have one small magic mushroom forest up on the highest level in the central northern area, where my main character lives. Gradually I will convert Bamboo Bluffs (the whole west and north-west area) into a proper region with properly arranged flowers and an actual layout rather than the random mass of nature junk that's up there right now. I wish I could apply a 'steam' effect to the lake up there to make it look like a natural hot spring. (Be really neat if you could also swim in the rivers rather than just in the sea...I could pretend to go for a soak and it'd be awesome if villagers could, too. I wish villagers could use/interact with a lot more of the DIY and furniture stuff in general. I want them to go IN the pool, or get in a teacup and whirl around on the ride! Too much work in programming?)
I don't really know what Nintendo plans to do with New Horizons once a year has passed as we should have every holiday already added to the game by then. Will they make the celebrations a bit different each year? Add NEW events? Or just gradually stop updating, maybe.
I definitely care about completing the museum, so that keeps me going back on when there are new critters, and to do a quick check for Redd, but other than that I'm down to a very idle/detached play-style.
EDIT: I've noticed since restructuring the island, I now find my villagers wandering EVERYWHERE. They used to stick right to town square and the eastern beach, and a little bit to the north east corner where my 2 player character houses are, but now they're all over. I found both Reneigh and Walt up on Bamboo Bluffs this morning...Reneigh was sitting on the ground eating a Fudgesicle and Walt was just walking until he decided to whip out a dumbell and start pumping his guns. Nothing special, in other words. They both live way out in the east-most section, and Bamboo Bluffs is to the far northwest. It was always possible for them to go there, there were inclines and so on...but they never did. What changed?