RST is pretty decent once it learns what files etc you access most. In your case yeah I think its worth at least trying for a little while. Say for instance you play Skyrim lots, all those levels etc will be loaded in the ssd, meaninging really fast load times. Then a few months pass and you dont touch skyrim, the skryim stuff will be back on the mechanical and say a few other titles are now in the ssd - bf3 etc.
It also depends on what size ssd you intend on using, if its <120 or so gb then yeah by all mean RST is the best option by far for best overall system performance. If though say its a >= 250gb or so then maybe its just worthwhile having just the os and most things installed on that and using the mechanical just for your mass storage (backups, rendered files etc.) My 2c on the matter anyways hope its of some help.
I'd personally just do it myself - put the OS on, the software I use most, and then put games like skyrim that I both play a lot, and have a fair amount of loading involved. for example, I wouldn't put games like SWTOR on the SSD which have really clever instancing.