There are several royal residences.
The main one is the Royal palace in Sofia. Now it is a National Art Gallery.
Vrana palace is located outside Sofia. It was build by Tsar Ferdinand as a summer residence. Its much bigger then the one inside Sofia. In 1998 it was returned to the Royal family and now Tsar Simeon II lives there.
Exksinovgrad palace is located outside Varna. It was build by Prince Alexander Battenberg. Now it is an official government residence.
Battenberg palace is located in Ruse. It was build by Prince Alexander Battenberg. Now it is a Historical Museum.
Tsarska Bistritsa is located in Rila mountain. Its big and beautiful palace. It was returned to the Royal family and the wedding of Princes Kalina (Tsar Simeon II daughter) was there in 2002.
There are other two residences in Rila mountain. One was build by Tsar Ferdinand and the other by his son Prince Kyril, both of them were returned to Simeon II but I do not think he uses them. During the winter its almost impossible to reach them because they are high into the mountain. In one of them there are pictures drown by Princesses Eudoxia and Nadejda (Ferdinand I daughters).
Another palace was Krichim palace. It is located outside Plovdiv and it was the favorite one of Queen Giovanna. The palace was also returned to the Royal family.
The last palace is located in Banya. It was build by Tsar Boris III. It is really small, its more of a big house then a palace. It was returned to the Royal family. And as long as I know on the Simeon II Bulgarian passport it says that this is his permanent address, not the palace outside Sofia.