++++++++++++++++++++++++9000 to all Restless Bohemian said.
I'm waiting to see the management aspect of the game. Building coasters is fun but gets boring fast, while management and evolving a park over time is much more exciting to me.
The guests are already behaving in interesting ways with groups and reactions . I'm hoping Frontier intends to build a lot of interesting systems on top of this. A few misc. thoughts:
Guest Systems I'd love to see:
Reactions to weather (seek cover from rain, ride water rides in heat), reactions to "behind the scenes" aspects, awareness of previous rides / order of ride (ride high thrill then gentle to calm down).
Specialized Parks / Marketing (guest expectations)
I'd love if there were management strategies that didn't involve a "perfect blend" goal. That is, I don't always want to cater to all kinds of guests: sometimes making a kid park or thrill/coaster park can mix up the experience.
A marketing system, like Bohemian suggested, could allow you to appeal to certain kinds of guests.
Here is an example in Jurassic Park Builder on GBA:
https://youtu.be/XYQOJjoKcgs?t=3m46s
He flips through the options quickly but each page is a particular magazine, tv show, or search engine you can advertise on.
That way you could market for kids and have only gentle and mid thrill rides and because you are attracting the right customers (e.g. marketing on kids shows) then guests are happy. Or, if you incorrectly advertise in extreme thrill magazines then you could attract coaster friendly folks who would be unhappy in your kid park.
Advertising signature attractions would help draw certain kinds of guests as well.
Parking Transportation Resorts
While not essential to what excites me about the game I'd love to be able to build my parks with an eye towards how my guests come in and how they might stay: a day park is different than a resort park. It would be fun to plan how guests travel between parks, parking lots, and hotels on disney style monorails.
However,
The big complication here is time scales: I definitely want to evolve my park over multiple years without spending real life years playing. If in-game days are short (e.g. around ~10sec in RCT1) then either guest animations/behaviors are out of sync with the in game time or they get sped up and we've got a bunch of fast moving ants flying through our parks. Neither is ideal and it's a tricky problem.
That's why its a bummer that the alphas aren't putting as much focus on management: there are lots of systems that could be added that have complicated interactions. It'll be a tall order to get all of those working really well while at the same time pleasing the folks are still complaining about coaster realism/freedom.
I have great hope that Frontier pull it off! Good luck to the team. I'm very excited.