When thinking about my career overall, I broke things down into small company/big company and buy side/sell side (or customers and vendors). I think you are likely to get different experience from working at each. This may be less true if you're a pure developer/engineer, but if you want to gain experience of the business side of things as well, it's really useful to know what it feels like to be the person on the other side of the table.

So far I've worked for a small software house (so, sell side) and tried to do a startup. I'm now contracting for a big corporate (buy side). So I guess that's two down, two to go.