Jim Hensen's "The Storyteller" series is a great reference for storytelling in general, in my opinion. I use part of one of those as patter for the one good poker trick I know.
For "This, That, and The Other," I tell a story-based version called "My Favorite Game" that ends on a blank card. For that one I pretend I learned the trick by watching somebody else do it, but the person I describe sounds like he's actually me. The story gets a little wonky with that one, but the patter itself is pretty straightforward.
For my 3-coin routine I start with a story about that one coin trick everyone's grandfather does while I'm producing the coins and rolling into 3-fry (available on T-11, ungimmicked 3-coin vanish, GET IT if you don't have it; I finish the routine with Silver Dream, which leaves you relatively clean and is also a really good routine).
With sponges, I claim I'm manipulating balls of raw magic.
The cups and balls is kind of like a cross between a game and a brief, light-hearted lesson in magic history. I draw on a lot of influences for that routine, but if you're interested in presentations that are completely metaphorical (where you refer to your props hardly or not at all), you should check out Suzanne's cups and balls on Youtube. She presents the cups as a parable and nails it.
Most of my presentations, stories, justifications, etc. are somehow rooted in a character, in this case a pink wizard from a fictional universe. To figure out how you should be presenting, you should figure out what kind of character you're playing, along with how and why he or she does magic. That will help determine whether you should be pretending to find loopholes in physics, talking about syncing up bodily energy to interpret brainwaves, or telling whimsical tales about your travels to India or whatever. Different effects will also lend themselves to different styles of presentation and patter.
