Sputnik
It's a very easy craft to fly the best way is to fly to about 70km then burn prograde at apoapsis. If for some reason you fail to achieve a stable orbit it will be fun to watch Sputnik decay in a high atmosphere orbit ;) Action Group 1 to extend the antennas as you will see they will be destroyed in the atmosphere otherwise...
SpaceX ITS
Cassini-Huygens
Rosetta
Send Rosetta and Philae to explore asteroids to your hearts content, but be careful some asteroids don't like to be touched.
Vostok 1
Voyager 1 & 2
Apollo–Soyuz Test Project
Surveyor
Pioneer 10
Luna 17
Hubble Space Telescope
Fun and usable orbital telescope launched via the Space Shuttle
Ulysses
BepiColombo

