For sheer wiz-bangery, you'll want this: http://www.artlebedev.com/everything/optimus/
. Never mind that it's mechanical, or from what I hear not that fun to type on. It'll make your Logitech G15 (or any newer Logitech with a screen) seem like a cheap Fisher Price toy. The entire concept of it is pretty damn cool.
Here's the thing about those Logitech screens. They're stupid. I have one on my G13 game-pad. The G13 is not stupid, especially for left-handed gamers like myself who tire of remapping everything to pl;'. However, the screen on it is of very little use and IMHO it looks silly.
Media features -- those can be had on any $20 keyboard. With a Logitech, you're paying for the macros, which can be nice, and for the screen. Since you don't use macros, and since you don't like mechanicals, I say your best bet is to look at ergonomic models. Yes, they take some getting used to, but if you want a truly better keyboard than what you have now (and your hands will thank you later,) take a look at at something like the Microsoft Ergonomic 4000. If you don't want something that big, then look at some of the higher-end curved Microsoft Desktop Set models (like the 7000 or 8000.) They're sleek like the Logitech, and I find the slight curve to be more comfortable than a traditional layout without needing to learn how to type again.
Keep in mind there's a reason everyone pushes the mechanicals. It may require a leap of faith on your part, but once you try one you won't go back.