Even as big a fan of the books and films as I am I've gotta say this is always an issue that makes me laugh, in fact I rang up a radio station about it when they had a segment on movie plot problems.

t: Really, you could have finished the story in 45 mins. Would have loved to have seen this scene instead:
Gandalf: The Ring must be destroyed!
Frodo: Ok, lets get one of those giant eagles to fly it over and drop it in the volcano.
Gandalf: No, we must form a fellowship and track through the lands of middle earth going up against various perils and dangers!
Frodo: Ah....Why? I mean we got the eagles it'd be a hell of a lot easier just to..
Gandalf: No! We must journey through the darkest reaches of Middle Earth and battle our way through greats beasts and enemies of the Dark Lord!
Frodo: Dude we could just save ourselves a crap load of trouble and just fly the damn thing over, do we really need....
Gandalf: We must have our wits about us at all times, be ever vigilant, and engage in war to free the peoples of Middle Earth once and for all from the grasp of the evils of Mordor!
Frodo: ...........are you effing high or something? We've got freakin' giant eagles at our disposal! On top of that, your a wizard, can't you just like conjure up some spell or something to send the Ring to Mt Doom. You're suppose to be a wizard, where the effing hell is the magic?