a ssd will wear out faster and will perform slower when near to ful, 10 to 15% should be always empty
i usually move documents, steam library and downloads to the other hard disk, in fact i moved the destination of those two folders, also desktop folder
right now only office 2013, windows, antivirus, steam app and a couple more programs are on my ssd, later will put origin and ubisoft again, but those are small, so the ssd should be almost empty
you can always go for a big ssd only, a 480gbs ssd and don't have 2 drives, but we are talking there about price
so this approach i think, will offer you the most of both worlds
there is a extra step, move pagefile.sys from the ssd to the hard disk, should help to keep the ssd healthy for more years