I have a couple of things I hope make it in,some minor,others less so.
1. More themes. In particular I think a dinosaur theme would be greatly helpful. So many theme parks had or currently have dinosaur-themed rides,such as Dinosaur at DAK and the now-defunct dinosaur ride at Knott's Berry Farm,I think it'd be very helpful to add,as many would probably be interested in such a thing. "Retro" themes would also be nice,as seen at Knott's Berry Farm and Disney's California Adventure with the 20s boardwalk themes. Lastly,a "spooky" theme would be fantastic,as almost all theme parks have either seasonal or year-round "scary" attractions/mazes.
2. Realistic water rides. Rapids,log flumes,chute the chutes,and any other variations of those. Almost every single amusement park on this planet has one "water" ride,whether it be a simple boat floating through the water to tell a story,or a flume style ride,so this feels like the most necessary improvement of all.
3. Transport Rides. Planes,trains,and automobiles! Just kidding. Probably something closer to trains,monorails,and ferries.
4. (This one is kind of odd) I notice this mostly on either water rides or in amusement parks with high capacity attractions (think Disney),but in many rides such as Big Thunder Mountain most famously,you'll notice guests board in one of two stations,which then merge into one track. This isn't hugely important or anything remotely close to it,I just think super detailed stations with individual queue lines for each row of a coaster,plus multiple stations for one ride are an awesome little detail that could be added to really move stations above and beyond. I also saw someone made their own (non-functional) "transfer track" in this game for extra coaster trains when they're not in use,which was incredibly innovative on their part.