As a heavy C3 user who used to contribute to the Suggestions page, I've had the same experience and share the same view as dop2000.
To add to newt's comments, a huge flaw with the limited vote system is that you're expecting people to keep their votes current with what they think is important. I'm not sure how many people are constantly going back to that site and aligning their votes with the ever-growing list of ideas.
So at this point, I'd wager it's a mistake to judge the ideas by votes. The longer the site goes on without rewarding those votes, the less people bother with voting. Instead, or at least in the case of people I know, they're likely just adding ideas to the pile, not voting, and hoping your team notices them.
Gathering input from users is obviously important, but this current system combined with a thorough lack of feedback could certainly be rethought.
EDIT: Sorry Ashley, I missed your bottom paragraph. I'll certainly have a think and dig around for alternatives