How would you liquidate a collection....

[Bkrum]

I am a long time collector who has been dormant for a LONG time (as in pre grading) and now trying to educate myself on the new realities of the card and memorabilia market. At some point (hopefully a long time from now) I will be charged with how to best market some portions of our family collection. While the collection is vast and varied I'm most interested in how one would liquidate high grade, RAW Topps and Bowman sets from the 50s and 60s. The sets have been meticulously upgraded by my father through the years and now are universally Ex-Mint with lots of really, really nice cards. I'm sure a trained eye could go through and cherry pick many cards for grading.
The question is how would one start the process? I couldn't imagine sending in entire sets to be graded but on the other hand I see lots of commons in auctions which sometimes bring big $$. I also know getting 8-9-10 grades are liking needles in a haystack. Do the large consignment houses work with grading companies or do you have to do that on your own? I was toying with submitting some cards for grading but I'm hesitant to do anything without thoroughly researching every angle.
I am not interested in, nor am i empowered to at this point to sell any of the collection. It is my fathers primarily and will be until he's not around anymore. Just trying to arm myself with information from the experts out there. How would you approach it? Any and all input would be welcome.