Let me start by saying the new Christmas tree update is awesome. I haven't tried it yet, since I'm not home, but it looks amazing based on the screenshots and information I've heard.
It would be interesting to see a larger selection of ornaments for the trees to customize as. It would be pretty awesome if we obtained them in a fun way:
1.digging-perhaps using the shovel can allow us to find ornaments in the ground
2-finding. Much like the easter egg hunt, ornaments can be hid around the map. Many different ones will spawn, some rarer than others.
3-a mini game: maybe make us get ornament points for playing some fun winter based game, and we can buy various ornaments with the points we get for playing.
If there isn't enough time to get all this done I'd be perfectly happy with just charging 100-200 gralats per ornament or making them free.
There could even be an ornament graphic contest, where the best ornaments win-or a custom ornament upload for 2000 gralats.