Congratulations! I have an S2 Space Gray too. I am not a very exciting user but I do rely on it to provide more than time and date.
I use Fantastical for my calendar app and I have it as one of my complications so I can at a glance see upcoming events. I like the heat beat complication also on the watch face as well as the outside temperature which I let Dark Sky handle because it will also tap my wrist and show me when rain or snow is stopping or starting.
I have toned down the Activity app. I only let it remind me to stand every 50 minutes (I work creating various media and I tend to lose track of time.)
I love the workout app and find it motivates me to add on to my workout.
If you have any macs that are running Sierra and 2013 or newer you can use it to unlock your mac. The watch will tap your wrist to let you know.
Also the S2 is much better at answering phone calls. The mics are much better than the ones in my S0.
That's all I can think of. You will love it. I have become very dependant on it. I like to leave my phone on vibrate only so the watch notifies me of calls and text.