I don't know much about SSD's other than: 10,000 re-writes? Right? I think? and they are lighting fast.. Good for a boot up hard drive. Which is what people typically use them for, to boot their O.S
Yah honestly, I would only throw your O.S on it, and if your a gamer, throw some games on there. Just make sure you don't defrag an SSD. It has very good read/write times and such. I'm thinking of grabbing a 64gb just for those purposes. Everything else should be stored on a reg hd, there is no point to getting one other than what I mentioned tbh.
I think it would be a good idea to buy a small SSD, such as a 40gb, as they are less expensive than the larger ones, and use that as your OS drive. Then go for a large regular HDD, perhaps a 7200 rpm, 32mb cache..., for all other data