For the lighter tasks I have I thing for the 12" G4 PowerBook. This is my... 6th one.
I use it probably as much as I do my quad i7/16GB/twin HDD/1080p display main machine. Absolutely all of my writing is done in Word '04 on the absolutely luscious keyboard.
I have never used a laptop with a better keyboard, ever. The love started back in '03 when I bought a brand new 867Mhz machine and was smitten with it instantly, so was the person who broke into the family home apparently. It was replaced with another 867 that was used through the end of high school and into Uni, where half way through the school term it rained while I had the roof down on my car. That 867Mhz machine was replaced by a 1GHZ which was used until I got a great deal on trading up to a 1.5Ghz machine. The 1.5Ghz had a faulty logic board (VRAM) so I bought another 1.33Ghz parts machine to resurrect it, but they weren't compatible, so the 1.33Ghz machine ended up getting the HDD/RAM/Airport etc from the 1.5Ghz machine. I sold that in 2012 or so, lived with the HP I have now for 3 or so years until I just had to have another one. Another 1.33 this time.
I tried to buy an Air at the time, but I just... couldn't. The 12" PowerBook G4 is, in my eyes, the greatest laptop ever built, ever.