I listened to Vaughan Williams today (Tallis Fantasia etc on Naxos). I don't know what I am missing in his music but I find it boring. Nothing seems to happen. It's all white snow to me.
Yeah, but we need to take into account that you dislike several other composers who people rank even higher than RVW - I guess his style just isn't your kind of thing

The Tallis Fantasia does use its material with economy, but to most it is highly effective. The symphonies are more in line with traditional expectations (the no.1 symphony is a fully choral one - almost to the point of being an oratorio - and somewhat influenced by Elgar), but I don't think it likely that you will enjoy his symphonies very much either. If you were to try any, perhaps the 9th, as even the 6th, which is commonly recommended as another side for people who are used to RVW's "happy" style, could probably be considered as "simplistic" by you. I would consider the orchestration more "to the point" than simplistic, and bursting with melody.
Edit: I guess my point is, don't try too hard to like him, he may be a "blind spot" in your interests, or if you do make an effort to enjoy his music, perhaps make sure that your expectations are ones that he can meet, rather than getting disappointed at him not being something else.