I’d recommend plain black captoes (like the Allen Edmonds Park Avenues), but you could also probably go with burgundy or brown captoes. Less formal would be brogues and wingtips. Tough to really give a concrete answer without knowing your budget or if you live in a location where you can snatch something up quickly.
Whatever you do, avoid wearing loafers with a suit.
ADDING from Anon:
“White OCBD with knit tie go well with the JCrew Ludlow suit?”
Some people don’t like button-down collars with suits, but it works if it’s casual.