Our first steps into a larger world is returning to the moon and setting up a moon base. There are countless benefit to living on the moon. Its a lily pad to go to Mars. Better at spotting near Earth objects. Haveing a second heavenly body for mankind to live on in case of the unthinkable happens on Earth.
Low Earth orbit has been beaten to death with the shuttle and International Space Station. The whole issue is funding, limited to no funding puts a stop to all of it. Until humanity realizes money is not everything and simply decide to go back simply for the Human condition then it pains me to say that we will never return.
Absent a century/centuries-long terraforming exercise, Mars won't be human-habitable without support from Earth. The moon will never be human-habitable without support from Earth. While I'm not saying that we shouldn't go there or even that we shouldn't do terraforming, we shouldn't expect that this is a serious backup plan for the human species.
Also, if we're looking at a moon base, the cost of building and maintaining are astronomical. Here's a rough approximation, based on units of Falcon Heavy payloads (~20,000 kg) at about $200M per (guessing $120M for the rocket, $80M for the stuff it's carrying). I'm guessing that I'm within an order of magnitude, but probably low.
Building a base for ~25 people: The ISS took 40 space shuttle loads to build, supporting 6-9 people. The shuttle carried about the same amount of stuff as the FH to the moon, so let's say about 50-100 flights. Cost: $10-$20 billion
Design and engineering: Land side, this is about 20%-30% of a building's cost. Let's go with the high end and say $3-6B
Management, planning, etc.: Everyone hates this number, but there's no way to build a project without it. Probably $5B
One time costs: $18-31 billion
Resupply: The space station gets about 20,000 kg of stuff per year to support 6 people. This gives us 4 or so FH flights/year for stuff, plus some crew transportation. Let's say 6 flights a year, or $1.2B/year
Ground costs, administration, etc.: $1.2B/year
With repair and other miscellaneous costs, we're looking at about $3-5 billion per year all up.
Just so we can look at the scale of this, you're looking at a program that costs about the same amount per year to maintain as the National Parks system, not even counting the one-time costs for construction. Let's be real. Our elected representatives don't have the will to fund something like this because it would be awesome. It's really hard to raise taxes,and it's really hard to cut programs. Congresscritters definitely won't take away funding from stuff that affects their constituents to fund something they can't see. Why would they? This isn't going to happen unless someone can either make money on it or an extremely wealthy private sector individual decides to make it happen.