Sadly I am also in your situation exactly. My father just passed and his collection is mine.
Now we talked prior to him going in hospital and his one request is that each kid gets a Glock. So I picked out one for myself and two siblings but there are a lot of guns/rifles-around 40 that I'm not sure I want to keep all if them.
I too feel guilty as this was his passion.
I will go thru them and keep the good ones: his 1911's, Luger, as s&w 357, am-47 etc. but some of the misc. .22's and odd rifles I don't really want and they were not sentimental to him or me.
So I do agree with the auction but do keep a few to be handed down at some point. It would be what he wanted. Just like my dad knew I would not keep all but some would and be passed down to my son and daughter. And that I think would have made him happy.