I'd love to see the dock become a grid of favorite apps. I tend to use watch faces that have lots of complications so I can tap right in to oft-used apps, so I don't get to enjoy some of the other faces much.
It would also be cool to have some way to quickly access some sort of smart stack of widgets. It's kinda cool on my iPhone that I can have a smart stack with Maps that will show the location of my next appointment, and a tap will take me into directions there. On the Watch, I'd have to have a watch face in use that has the calendar complication -- or press the crown and choose calendar -- tap into the event,
I also hope for more flexibility with the Ultra's action button. For example, I've got it set to Stopwatch. I can start the stopwatch or mark a lap by pressing the button, and stop it by pressing the action and side button. But what if I just want to see the running stopwatch? And if I set it to Waypoint instead, I can only set a waypoint. There's no action+side buttons function (view last waypoint or the list/compass could be useful).
Also, there's no way to have the action button do app-specific functions while in those apps. I'd like to be able to start and pause a workout with the button when I'm in the Workout app, but keep using it for the stopwatch when I'm on the watch face.
It could be cool to have the option to set the action(+side) button's functions dependent upon the watch face, by choosing a special complication. So if I'm on Wayfinder, I could assign it to my waypoint complication. If I'm on Chronograph, start/pause it.
Basically, I think there's a lot of missed potential here.