Munich to Lyubliana train or bus.

I took the bus in 2015 and simply don't remember the trip. (I probably dozed off and on.) The bus was certainly comfortable enough, but unfortunately I can't comment on the scenery. I'd be surprised if there is a really significant difference between what would be seen from the train and the bus.

I flew back from Zagreb to Washington DC with a single connection, I think in Amsterdam.

There isn't a large difference in terms of scenery. Even though they do not follow the same route, both go through a number of tunnels when crossing the Alps and the rest of the trip through the valleys offers plenty of lovely scenery, although you may encounter limited visibility on the bus at times due to anti-noise barriers. You also can't move around freely like you can on the train, but it shouldn't be too big of a difference. For buses, look into Flixbus and Arriva, they both service this route.

The train is probably more useful if you are not going straight to Ljubljana but want to visit Bled first. The train stops in Bled, the bus does not and requires a transfer in Ljubljana as far as I know.

Stop in Bled! it is lovely!!

Thanks, people. Is the train station near the lake? Hope so.

As far as mysterious connections from the airport, Take either the S2 or S8 trains from the airport train station. They alternate every 10 minutes and take different routes, but both going to where you want to go. For the train you want to get off at Hauptbahnhof (main train station) and the bus, get off at Hackerbruecke for the ZOB (central bus station).
Cost is 11.20 EUR per person.

The train station is in the town of Lesce, 10 minutes from the lake. You can take a local bus to the lake from the train station or hire a taxi.

FYI, Bled Jezero station is closer to the lake but Lesce Bled station has better schedules for your direction of travel. The local bus or taxi is easy enough to get to your accommodation.