We could propel a 100 kilogram robotic craft to Mars in a few days. If you want to push something like shuttle class, it takes you roughly in order of month to get there, within 25 year light of Earth, there are actually quite a few potential exoplanets and habitable things to visit - that may be habitable. We don’t know of course. There are many targets to choose from. The closest is Alpha Centauri, which is about four light years away.