An overnight guest usually only requires a soft place to rest their head and a clean spot to wash up, but take your hosting skills a step further by welcoming them with a little treat. I've got a list of my immediate family and close friends' favorite confections, and whenever they're staying at my pad for the night, I always leave a bag of their favorite goodies on the bed waiting for them.
If I'm feeling extra ambitious, I'll wrap it up in something pretty with a tag that says, "Welcome." For everyone else whose sweet spot I don't have noted, I'll just put out an artisan chocolate candy bar or something most folks will enjoy. It's a simple gesture, but it goes a long way toward making visitors feel welcome.