In my opinion, an SSD for a boot drive is pretty much essential now. I have one a 120gb SSD for my C/drive, a 2tb D/drive for mass game strorage, and another 250gb SSD for my most/current played games, and I fully intend to put Star Citizen on its own 120gb SSD when it hits beta. Once you start get used to load times of an SSD there is no going back I'm afraid.
I used to play BF4 and Hardline of a HDD, by the time I logged in the flags were already taken, by players with there game on SSD!
Edit:
In case you didn't know there is a program called 'steam mover' that allows you to swap games from one HD to another, handy for having a smaller SSD dedicated to games your playing, so when your finished playing it you could use 'steam mover' to move it to a large HDD. It's what I do and it works like a charm