Laura The Long Mars name checks KSR's Mars Series, which charmed me. On a very high level of abstraction, they're similar. Instead of trying to build a better world, most of the folks in this series are trying to find one. The Long Earth series is much gentler, and less complicated. Far fewer characters; far fewer zero-sum conflicts. None of the characters in this series are as vividly drawn as the ones in KSR's, and there's more whimsy. It's not hard science fiction; even granting the "step" technology that lets you set across worlds, it's still got some big fantasy elements. Or whatever you call it when a Tibetian motorcycle repairman gets reincarnated as a computer. The ideological conflicts are there, but again, not as vividly drawn as in KSR's books.
John (Taloni) Taloni The Long Earth series has some sociological commentary, mainly on colonialism, and fairly decent characters. It lacks the technical focus of Robinson's Mars series. But it is serviceable fiction. Each book is fairly short. Give the first one a try.