Ello..
I have got 2 Macbook Airs, 1 older style and 1 newer style.. Which screen size where you looking at?
They are great machines, the speed as you said is great. 128G is plenty of storage.
I used to have alot of music, that would take up a vast majority of that space, but i use things like Spotify and ICloud for music/videos. So 128G of programs and word documents is an awful lot!
The only downside (not a particularly big problem) but they do tend to get a little hot, especially when using while plugged in.
I have got a Macbook Pro i use for work, which has pretty much the same feel when using. The only obvious benefit is the CD drive. Which does come in handy!
If your looking at getting one, i would definitely recommend the refurbished section on the Apple Store. Its not a massive saving, but its basically a new product in a blank box (Or at least mine was)
Cheers Josh.