Based on a two day trip to Ljubljana in 2007.
Although I only passed through Slovenia by car and train and spent two days in Ljubljana, I was very impressed with it and would love to come back. It seems like an extremely scenic country with lots of unspoilt nature including beautiful forests, mountains and rivers. Ljubljana is a gorgeous little city, with a really pretty historical old town surrounded by a river. From Ljubljana Castle, you have an amazing view of the city and its surroundings, wooded hills and high mountains as far as the eye can see. There are tons of cafés, bars and restaurants all in the small lanes of the old town and all along the river. And while the city is already very picturesque during the day, it gets even prettier and livelier at night when everybody is sitting outside on the various terraces to enjoy a warm summer night.
Useful links:
Lonely Planet Ljubljana
BUG Ljubljana