The 60x30x45cm tank is okay, but you can only stock as much as a 60x30x30cm due to the same footprint size. They're a really good medium sized tank to work with, I have two 60x30x30's. Add a 50-100W heater and you're ready to go.
Fish wise I like to go with one or two "feature fish" and a handful of shoaling fish. You could have either a male Betta, a pair of dwarf cichlids OR a dwarf gourami along with a small shoal (6-10) of the smaller tetras. If you upgraded the filter and kept the shoal small, you could add a few corydoras or small bristlenose catfish to help clean up. If you want something more unique however, dwarf puffers could be another way to go but they can be a bit sensitive at times.
HTH