Casual Interplanetary Travel

Currently it takes about 20 million dollars of government support to get a single human being into Low Earth Orbit, and only robots have gone beyond the moon. Aside from the massive cost there are supply considerations because getting just about anywhere takes months if not years. However, in many stories involving space (and nearly all outside of literature), even if interstellar travel is hard, interplanetary travel is easy, taking a couple days at most and within the range of at least an upper-middle class person cost wise.

In context, it's not that bad; Historically, all four of Christopher Columbus' voyages combined didn't cost 20 million - and once you reach orbit, you're halfway to anywhere. Once the infrastructure was in place, the original American immigrants made their journeys on personal funds - so there's no reason that the phenomenon shouldn't repeat itself by the 2050's so long as we get a "space Mayflower" by the 2020's. Better get to work on that.

Sister Trope of Casual Interstellar Travel. Sometimes there's minimum range limitation that makes only interstellar transit easy (say, wormholes), sometimes interstellar travel is still sublight or very difficult, but this is easy.

Examples of Casual Interplanetary Travel include:

Anime and Manga

• Subtle examples can be found in the Gundam series, which likes to use Lagrange points around the Earth for its colonies, with the furthest ones at the L2 point (where the Principality of Zeon is located) being past lunar orbit. The L3 point (where Mobile Suit Gundam begins for example) is on the opposite side from the moon at any given time. Travel between these points, or from one to the Earth or the moon, takes a few days at most. Going out past the immediate area of lunar orbit, however, takes several months.
• Aria has people from earth regularly visiting Mars for business or pleasure.
• Lyrical Nanoha series is a bit vague about its cosmology but it seems that "dimension", "world", and "planet" mean the same thing in the setting. Spells like Dimensional Transfer are readily available to Magitek mages, and in Nanoha Vivid, the heroes take a shuttle to another planet like one would take a bus to another town.
• Cowboy Bebop has this, with the constantly broke protagonists nevertheless able to afford to operate an interplanetary fishing(!?) ship. This is facilitated by hyperspace, however.

Literature

• In the Honor Harrington series, travel between planets is casual to the point of day trips to other planets by middle class people being possible (with favorable orbital positions).
• In Alastair Reynolds' novels, interstellar travel is very arduous, as he is strict about there being no FTL travel in his stories. However, interplanetary travel is portrayed as relatively casual.

Live Action TV

• Firefly has this, as The Verse is confirmed to take place in one large, multi-star system.
• In the Canadian show Starhunter, interplanetary travel is semi-realistic but casual; push on the gas and you go faster, but it does take a couple of days to get from the moons of Jupiter to Mars. Interstellar travel exists (via Hyperspace), but is very new, cutting edge, rare, and dangerous.

Western Animation

• Exo Squad has people travel between Earth, Mars, and Venus, as if it were to another country.
• Used for a few gags in Futurama (which flip-flopped between Interplanetary Voyage as the plot or humor demanded), most notably in the second episode, when Fry is still new to life in the future, and the crew is getting ready to take-off and make a trip to the moon.

Fry: Can I count down? Leela: Huh? Sure. Fry: Ten...nine...eight...seven... Leela: We're here. Fry: *quickly* Sixfivefourthreetwoone blast off!

• • Interplanetary travel is like crossing the street. Cubert and Dwight built a craft capable of doing it; they found it in an ad in a comic book. In another episode, Fry laments that he'll "never get into space" because his brother got to Mars first. Leela points out, "You went [to space] for donuts this morning."