Bono's voice is like a saxaphone, and I'm not terribly supprised to hear of an un-conventional approach to recording him. When I listen to U2, rich and warm is not what I want to hear, I want to hear Bono's voice cutting through like a hard sax.
Now for the OP, as has been said countless times, it really depends on the voice and the song. The 58 you mentioned is going to be the wrong mic far more often than it's going to be the right mic though. IMO, anyone planning on recording vocals should have at least one LDC (large diaphram condenser), and it should be one that isn't overly strident in the upper mids like a lot of cheap condensers are. There are inexpensive LDCs that fit the bill. Also, there are a couple of large diaphram dynamics that are well into the warm and rich catagory, like the RE-20 or the SM-7. Ribbon mics are also good at warm and rich.
To keep it warm and rich though, you need to follow those mics with a preamp that isn't going to turn it back to cold and brittle, or sterile. For the ribbons and large diaphram dynamics, it also has to have a lot of gain. There's a ton of discussions on this in these forums, so spend a bunch of time reading, and try to get to a pro audio store where you can hear some gear firsthand. Also, check out thelisteningsessions.com and other gear shootouts for a little more listening.