Adam and Sam, you should start with
FROM RUSSIA WITH LOVE - the straightest of them all without any gadgets and still close to the book!
then GOLDFINGER because this is where the classic Bond formula was found and established which lay the foundation for all the Bondfilms until the latest reinvention of the series with CASINO ROYALE.
ON HER MAJESTY´S SECRET SERVICE has to be in there - the first time they allowed Bond to be a little more civil - he is getting married. If Connery had done this one, OHMSS had been the best Bond ever possibly.
To cover Roger Moore´s Bond territory they certainly should watch THE SPY WHO LOVED ME - one of the most successful Bondfilms ever, an action classic and one of the 70ies´ biggest box office hits, Moore´s personal best liked Bondfilm and due to John Glen maybe the pinnacle of what one could do in cinema with a Bondfilm. (And by the way - it´s just great fun and never gets boring, even after all these years!)
Certainly LICENSE TO KILL should be next to include Dalton. It´s the first attempt to leave common grounds and make Bond more personal, dangerous and less womanizing. It´s a great film, yet the audience did not respond well. Anyway...
Finally to close out with Brosnan - in my opinion the best Bond since Connery until Daniel Craig blew all of them, including our beloved Sean skyhigh out of the water and into oblivion (I AM SERIOUS) - Adam and Sam should watch THE WORLD IS NOT ENOUGH, the third attempt to varify the formula a bit more...the opening sequence is over 20 minutes, that was new! And to close it all they should at least watch the first half of DIE ANOTHER DAY to witness how well it all started for the anniversary Bondfilm and how terribly ridiculous the series turned itself into when Bond travels to Iseland in the second act...this is where Adam and Sam, to prevent them from lapsing from faith should switch off their dvd-players.
It would be a great marathon! So DO IT guys since you are no Bond enthusiasts...but it is a phenomenon, so come and taste it...