I'm not sure about how long it would last - I haven't used it heavily since my Filco showed up - but I liked the Microsoft Bluetooth Keyboard 6000 I still have around.
Advantages: Never had any problem with the Bluetooth, Scissor Switches and a nice compact layout with a slight curve. There's a version that comes with a separate numpad (has "Mobile" in the name).
Drawbacks: Somewhat flimsy power switch, bluetooth search button and battery cover, no feet (fairly flat, a bit of an incline), no Caps Lock light.
If you're not hauling it between multiple computers every day the only point against it is the flatness, which isn't necessarily a disadvantage if you're not someone that uses keyboard feet.
Other wireless keyboards I've also used (both scissor switch):
Apple Wireless (the mini bluetooth one) - nice, but the layout can be awkward for Non-Mac use and the keys have gone to **** on mine, though not super-quick or anything.
Kensington Slimblade - Not as compact (fairly standard tenkeyless with a separate numpad) but no excessive bezels or anything, non-bluetooth but the receiver stores nicely in the mouse. Dust gets everywhere. Switches not as nice as others, and weird and awful multimedia keys on the top.