This is quite difficult! I'm assuming weather and comfort don't matter to a ghost, so it's purely about how the outfit looks. How would I want to be seen for eternity, doing day to day stuff? I think I'd aim for smart casual with layering, so dark wash bootcut jeans, my ruched boots, purple cowl neck knit top, scarf and either a jacket or cardigan. Of course I could go completely the other way and opt for something completely theatrical, but I can't think of something suitably over-the-top at the moment!
I also love Being Human; I'm planning to watch the season finale this weekend. Incidentally R+J, did you know that they're showing a one-off of Becoming Human in the same time slot this Sunday? It's a spin-off featuring teenage versions of the three types of supernaturals, including Adam from earlier in the series. Up to now they've been showing bite-size episodes on the internet, but due to it's popularity they're airing the whole thing on TV in one go.