Xur deserves to see more of Sol. He should be able to visit the cosmodrome, the derelict leviathan, the enclave or helm, and any other free-to-patrol location.
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I think his placement should be entirely random. Not just one specific spot per location. He should spawn in various corners and maybe even in some safe spots in Lost Sectors. And maybe he could be in featured Legendary Lost Sectors too, with special offers. Who knows.