Know-How Exchange : Advertising/PR

It's hard for me to imagine that a blind website submission for sponsorship is going to work well. You need to approach each prospective sponsor with a pitch that make it clear why the sponsorship would be a worthwhile and on-strategy decision for them.

A "generic" pitch -- like "90,000 people will see your brand name" -- isn't going to cut it. You need to tell them how that's going to translate into incremental sales and profit for them, or how it's going to help them accomplish some other important goal of theirs.

It's not about telling them how great your event will be for you or for the people who attend. It's about how it's the perfect fit for THEIR [specific] company objectives.

I'm with mgoodman on this. Unless you have a mole in the marketing department of every single national brand you are targeting, I can't see how you can know what's currently right for them. It's so easy to make assumptions that suit you on the basis of company's public statements and think you're customizing the opportunity. Every time we do that, we find the information we're working with is way out of date. In this economic climate objectives can change quarterly or even monthly.
Maybe you can run surveys to get information they might want to hear, or get an introduction through a contact, to get a foot in the door. Then you can find out what's currently important to them: and "them" means the individual making the decision. They may need to be seen to be doing a great job to stay employed. Convince them you can help them keep their job and you'll get the sponsorship, but not with general approaches. This is an approach that only works through cultivating a relationship with the key budget-holder.
Not what you want to hear, I know.