I only have 36 gigs free on my 160 gig SSD. That's only OS and applications. I keep my games on a 1 TB drive strictly for games, and I have another 1 TB drive for all of my media and data. If I keep taking advantage of the Steam deals, I may need to upgrade to a 2 TB sooner rather than later. Or just uninstall the ones I'm not actually playing, but why do that, right? Anyway, I don't know how much space most people need for their applications, but I don't even feel like I have that many, and I'm already feeling like I don't have enough breathing room.
I'd like to upgrade to a larger SSD for my main drive, though. While I've had zero issues, I definitely wouldn't be doing SSD by itself. I think I'll be glad at some point that I have my data on its own drive. I'd like to use my current SSD for my PS3. I don't use my PS3 enough to need the 500 GB that I currently have in it, so I think I'd rather have the performance versus the space.