"though I would be skeptical of any claims of pre-plague geneological connections."
Why would you be skeptical? That you're even here to be skeptical proves that some survived. Mediaeval society fell apart largely due to the plague, and so geneological connections are subsequently difficult to prove. But, there are those families who can prove them. The geneological difficulty in proving pre-plague connections most often hinges on the lack of a surname, going back in time. The practice is a sort of "Frenchification" adopted from the Normans, first appearing in royals and thence down the line to minor nobility and then to merchants and so forth. Freemen began having surnames around 1250, as best I can recollect from my reading.
960 in my lineage, and not a whiff of royalty anywhere.