Hello, guys
Well, let me tell you my modest opinion- yea, Sofia is definitely overcrowded already as well as Bansko and Sunny beach (unfortunately); especially the famous resorts. The secret is to discover virgin and beautiful nature, organic food etc.
As far as the investments are concerned- undisputedly the most perspective region is Vidin district (the socond bridge between Bulgaria and Romania etc..) So I would suggest to check DELETED BY MOD (advertising)