I'd say there's a great deal of tension at points in golf, on the final day of a major when the leaderboard is tight and every shot matters, and of course the Ryder Cup continually throws up drama.
I would agree that cycling is rubbish to watch, I know there are a few on here who are well into it and perhaps they understand the nuances more, to someone more casual it's incredibly dull.
Never got on with rugby league at all, NFL is a mystery to me and horse racing just isn't for me - I like a bet, but only on stuff I understand. Take gambling out of it and it doesn't leave you much as far as I can see.
I'd urge anyone who's vaguely into tennis to go and watch some top level stuff live if you can. The speed and athleticism is just incredible, you don't notice that on TV. Forget Wimbledon though as they have the worst ticketing system known to man.