Honestly I think lunar gateway is a decent idea, Its the easiest thing to do thats new as far as space is concerned and thus potentially the cheapest way to gain international co-operation, public interest, and potentially ignite another space race. Looking forward it can can potentially act as a life raft for any future lunar colonies in the event of a mishap. And while a moon colony isn’t as impressive as a mars one its much safer to practice on given that emergency re-supply can actually get there before the crew are already skeletonized. A moon base itself can then act as support for moon based telescopes (which have significant advantages, and disadvantages of course) and if you can get some kind of manufacturing going its far easier to launch from the moon than it is from earth, even if the moon just ends up as a glorified space gas station.