[DrMitchJ]

Okay, you have a Herculean task ahead of you! VERY time consuming, and VERY tedious, too.

Here's my 2 cents ... Bulk sell the commons. Don't waste time organizing them .... Eliminate them and that will give you 2 important things.
1) it will give you Lots of room
2) it will begin the process of setting up a dialogue with local card shops/collectors. You can feel them out, see who is better, honest, sleazy, etc. for future sales.
You will NOT maximize you returns on these base cards, but it will serve as important information for any future endeavors. Well worth the discount you will be giving, IMO.

Now, the better cards in the safes. .......
You have several choices to make for organizing them, based on how you want to sell them. first, take anything that is to be saved, keep them aside. Worry about them later.
With the rest .... Here are some suggestions
1) organize by player : some people and many collectors are only interested in certain Players ... This will help maximize sales to those individuals.
2) organize by team: some only collect a certain team.
3) organize by product line: some people are only interested in collecting Gypsy Queen, Stadium Club, Heritage, etc, etc. probably easiest quickest way to organize, IMO.
4) organize by price: $10 in this safe, $20 in safe #2, $30 in safe #3 ... Some people are only interested in higher priced cards.
5) have the better cards slabbed and graded. Some people only collect PSA graded cards, but will pay the most for High Grade cards. This is great, except for the initial outlay of money to have them graded.

Selling them by yourself, (even on eBay) is the way to maximize your $$$$ ... Flea markets, monthly card conventions. Buy a table, rent a space, take a weekend once a month. There is a huge cost to selling and a reason dealers don't buy collections at BV, they have to absorb lots of costs before they realize any profits.
Hope some of this is helpful.