A Roadmap to Interstellar Flight (2016)
If we could solve the energy problem, humans could go pretty much anywhere in the galaxy on a 1G ship. (ok there are other issues like actually building the ship, supplies (or a biosphere that can support life for decades), shielding,  but that's all easier with unlimited energy).For example, a ship could travel 1,000 light years to the Orion Nebula in only 15 years (as perceived by those on the ship). And since they are living in 1G, a lot of the detrimental effects of long-term space travel are eliminated.Of course, to an observer on earth the trip would take over 1000 years, so don't expect to hear how the trip went.