Great news! Wizz Air offer just moved South of the Danube!
20% discount for all Wizz Air flights to/from Bulgaria only today (14/12/2016). Just in time for a sky holiday in Bansko.
Bonus: new six routes from Varna to Dortmund, Eindhoven, Larnaca, Munchen, Milan and London.
Travel dates: 14.12.2016-31.12.2017
For accommodation I recommend you to search on HotelsCombined as it aggregates all booking portals including Booking. You can find hotel reviews on Tripadvisor which is also great for searching best places to visit.
Hostelworld offers perfect budget accommodation for students, backpackers and low cost travelers.
If you want to stay with a local, you should rent a room, apartment or house on Airbnb. When you travel on Airbnb, you will get €18 in travel credit as my referral.
I suggest to rent a car from RentalCars if you want to drive around these incredible destinations.