An interesting discussion...
There is a Denethor discussion on TORN and i'm just fascinated by the descent of Denethor BOOKVERSE. http://newboards.theonering.net/forum/gforum/perl/gforum.cgi?do=post_view_flat;post=1002471;page=1;sb=post_time;so=DESC;mh=25;
There is a controversy or it seems like there is a lot of conjecture that he didn't care about Faramir or fanfic has often wrote of him in an uncaring way towards his younger son.
However, even in the book ""'I sent my son forth, unthanked, unblessed, out into needless peril, and here he lies with poison in his veins." he does repent in the end and him burning Faramir along with him shows his unwillingless to part with him . Of course Denethor has already had his mind overthrown at this time by the palantir.
One of the points that i have gathered in the TORN thread above is that Denethor and Faramir may have had different viewpoints on how to govern. Boromir is more like Denethor in mind and probably politically, so therefore is more doting upon him and favors him. Denethor and Faramir may have different worldview to begin with so therefore at odds. But that doesn't mean he didn't love him. Gandalf was right that he will remember it before the end.
From another person in one of the message boards Denethor and Faramir are both introverted and scholarly, but they are also very different in their worldviews, which would make it hard for them to understand each other. (It's the age-old issue of a conservative parent and a liberal child.) Boromir in turn is more socially talented and charismatic so that pretty much everyone likes him, and I think Denethor is no exception. Boromir's ambitions are also noticeably more grounded and traditional than Faramir's, and I think Denethor likes that too.
I guess it is "progressive" to think that the King will return and that Gondor will have a King again? To have the kingdom ruled by stewards remain a "conservative" way of upholding tradition"? Even with Faramir accepting all that Gandalf has to advise and offer is contrary to how Denethor would rule, govern and decide things.
I guess i should write an essay or something haha. (in addition to the stories brewing in my head) :P