For your relatives without experience with vinyl, eBay or Discogs will take too long and be too much of a hassle, especially going through each record one-by-one grading.
Depending on where you live, the easiest/quickest thing for your heirs to do with you LP and CD collection would be for them to call up an area record store or three and ask for an offer on the whole collection (maybe let your heirs know the rough value). Assuming you have a worthwhile # of collectible LPs any record store owner will travel far to make a house call to pick up a valuable collection. Depending on the number of rare/collectible records, they'll probably only get 25-35 cents on the dollar, but will be quick and easy.