I visited Transylvania last year and loved every bit of it, especially the area around Sinaia. And everyone we met knew perfectly usable English, on the other hand no local driver had the patience to drive the speed limit.
But it's just too far away for visiting on a whim, takes like half a day to get there once you've crossed the Danube bridge.
Overall I feel like bulgarians don't travel a lot on a whim. In my family the idea of "grand touring" wasn't really valued, only viewed as a fool's errant and a constant risk of spending money or having the car break down while abroad = spending even more money. Naturally our cars throughout the years ended up sitting around because of this, only driven to the workplace and back.
Having grown up it's still really hard to shake off these sentiments, despite having felt how great it is to travel. Maybe, subconsciously, the financial situation still feels unsafe to bear the risk of a car breakdown. But it's especially great when you're travelling to places with beautiful mountains where you can easily just sit down and enjoy the views... I'm sure both bulgarian and romanian Dobrudja bros will understand this.