Bulgaria & Romania

Bucharest is a far cry from a major tourist sight. In fact, its a far cry from a mediocre tourist sight. Top sight: Outdoor Museum, collection of old Romanian houses. Tour the capital building, walk the grand boulevard extending along the fountains in front of the capital building. Walk the main drag are in the central city. Bus/train to the two towns (one Bulgaria, one Romania where the river cruises dock.

You can easily spend a wonderful day (or two. or three) in Bucharest! Tour The People's Palace I(a huge, monstrous affair! Strangely - you need to take your passport.), do a walking tour (there are several - I enjoyed one that focused on the communist era and the revolution), take a tram to the National Village Museum (where they have examples of houses/villages from all over the country), visit the National Gallery of Art I(very small but quite nice - perfect for a rainy day) go to the Atheneum for a concert (or find a ballet), and have dinner at a traditional restaurant.

Re the Rila Monastery - it didn't take us very long...maybe an hour... If traveling from Sofia, there are several nice restaurants en route, where you can have grilled fish next to the stream they came from.

I loved both countries - and hope you do too!!

You will probably need about 2 hours if you want to enjoy the Monastery inside and outside with its close surroundings. You may even have lunch in these 2 hours.
The Rila lakes may also take about 4 hours hike and that depends on how many of you are in the group, how many photos will be taken and how fast is your hiking pace.
Considering these hours, have in mind the time you will need to get to the Monastery and to get back.

Another quality visit is the National Ethnographic Museum. There are a number of fun restaurants. The Curu la Bere (Beer Wagon) is touristic, but fun - dancers do folk dancing, food is good. La Mama is a local chain, with again good food, Roumanian wines, and the charm of a local spot.