The local auction house is by far the best bet. They will probably have seen it all before and know how to divide all the stuff up into different lots. They should also give you a realistic estimate as to what the stuff is worth and then it's up to you whether you get them to put the stuff into their auctions. The auction house's valuation will also be useful for probate.
In addition, by doing the valuation and sale through an auction house you are avoiding any potential for comeback that you might otherwise get from selling on ebay.