NewbieNick

I've had this game since may and played the demo 1.5 years ago and just recently started watching Scott Manley tutorials. I've traveled to the Mun and Minmus a few times and returned each time. I also have a docking station in orbit around Kerbal at like 120km. So now I'm wondering which planets are easiest to travel to and return besides the Mun and Minmus.