So I took everyone's advice on styling this tube skirt, and I think I'm starting to figure it out. Many, many thanks to everyone! I went looking for a lower-contrast top, with structure around the shoulders, and not a knit. I found this pale citron top (the label says it's green, I think it looks yellow), with fluidity. It's comfortable, and perfect for the summer-disguised-as-spring we're having at the moment.
And now I can add to the "list of things I never thought I'd wear": a garment with "tube" as the primary descriptor. :)