If you are in Vienna during Christmas time, it is recommended to visit some Christmas market. The best one is definitely in front of Schloss Schonnbrunn.
Kamzik is a hill above Bratislave city. It is a nice place to go if you want to get some fresh air. You will find there TV tower with restaurant in the middle. The restaurant looks fancy, but after one dinner I must say “nothing special”. But it is worth it to sit down in the restaurant and watch around. You will see whole Bratislava and even Austria.