Oracle - I brought cartons of middle-of-the-road country collections to an auction house that I had done business with, and I had also researched various ways of disposing of the collections, as you are asking about. The house that I went with had auctioned similar things in the past as individual country collections. I lotted them up myself, with descriptions, values, etc, (I used to be a lot describer for a few auction houses, so I know what I am doing). Imagine my shock and dismay when I received my consignor's list and they were all lumped into one multi-carton lot. I have been buying and selling for decades and have a very good understanding of values. So...
If you want to get rid of the stuff, consign it with your choice of auction houses. If you want more control (if you consign it, THEY have control over how it is lotted, described, etc) go with
ebay, or something like that. If you consign, and get unpleasantly surprised by some aspect of the process, you are probably SOL. Needless to say, going the
ebay route will involve a lot more time/effort on your part. If you go the
ebay route, pictures always help, and close-ups of the more valuable stamps won't hurt.