Spamming is not good. But make every single bitcoiner write a person-to-person letter to the merchants, that's pretty good.
I think I see what he is saying, and it wouldn't be spamming, but there would have to be a good way to let a person know that 'x' amount of users want them to accept whatever it is form of payment.
I would also cut the automated emailing portion after a few days, and actually write an email after a few days explaining everything rather than having it automated. Tailor that email to their business type by noting specific things about Bitcoin and their specific business.
If somehow you could collaborate with the 1000btc business bounty and this idea
http://www.reddit.com/r/Bitcoin/comments/l0o54/bounty_1000_btc_for_getting_a_major_business_to/ ... or maybe close this thread and get that 1000btc, I'm sure you could split it with the business.