Hiya,
The major enterprise tools around are Brandwatch, Radian 6 (now called marketing cloud), Sysomos, UberVu and Synthesio. There are various others around, but those are the ones I'd recommend looking at first.
The WebLiquid report is really useful, as it compares some of the top tools. You have to give your details to get hold of it (no money though), but it's worth it. I'd recommend demoing the tools that most interest you, as this is the best way to see which suits your needs and takes your liking UI-wise.
Full disclosure: I am the community manager for Brandwatch (and found your question using our tool!)
Hope that helps,
Jasmine