As a 120gb SSD user , HOW!? Do you not manage what games you have installed at all?
If I own it and there's a chance in hell I might play it, I want it installed. To me, my steam library is analogous to my shelf of PS2 games, a large library a couple of clicks away. The other half of that 2TB has been reserved for Steam (I've just been using it for temporary data dump).
Also my connection is 6 Mbps, which is ~2.5 GB/hour. Steam downloads tend to jam up my connection increasing latency even for web surfing and renders streaming video near impossible. I prefer to do my downloads overnight or other non-use times.
I know the the feeling though, my laptops have 256GB and 160GB SSDs.
I manage my games by having them all installed. I play most games on a whim, if it's not installed, it's not getting played.
I also tend to add any steam keys to steam right away just so I don't forget that I own those games. Doesn't always work.