Hmmm... I never did like the idea of naming warships after non-legendary people or places, unless there's a
really good reason why that particular place/person deserves a warship (other than just existing/being semi-known and dead as seems the case for most US warship names these days. Anzio comes to mind as one of the few in use that I think actually qualify, as it was the site of a major naval landing). It just lacks the proper fear factor.
The RN got it right though, they actually name many of their ships in a way that tells you that you seriously don't want to mess with this thing. GTCv Warspite, anyone? You don't even need to see it, you just know it's going to be trouble if you run into it. Whereas the GTCv North Carolina doesn't score very high in that regard nor gives any indication of what kind of ship it actually it.
For medical and science vessels though, I pretty much agree with you. It's appropriate for those to be named for historical figures of their respective trades.
Now, for the actual naming:
I tend to give cruisers names of the *ous, *able and *a/ence variety. Courageous, Indomitable and Defiance would be three examples of that.
For corvettes, I go with whatever sounds reasonably badass, but without any real theme to it. Warspite is a favourite of mine (as you might've guessed by now), but sadly it's been used so it's out. As long as it sounds like it belongs in a fight, really, it's good.
Orion class destroyers get a name that imply the wrath of some angry god, which is about what an Orion equates to versus other capships. I particularly like Avenger, and use that as often as I can. I rarely use Hecates, so I don't have any naming scheme for those yet.
A special case is black ops ships, whether it be GTVI, SOC or some other entity. I almost always give those a sneaky or incorporeal name, like Shadow, Phantom and the like, regardless of which class they are.
Finally, mythological and/or legendary names can replace any of the above. Except black ops, which I think needs to be special since it should be an occasion whenever you encounter one, and so you should be able to recognize from the name that this isn't your regular run of the mill navy ship. Which of course makes no sense, as black ops ships would prefer to blend in, but I'm not going to give them that choice
