I have used PR agencies and other third party services for my startups in the past. In my experience there is nothing like the founder getting in touch with a journalist directly and 'selling' their product/service with their own passion.

PRWeb has done little for me in the past Pitch Pigeon is nothing more than a quick way of emailing a wide variety of blogs, who may be wrong for your product and the email might not get to the right person. It's to scatter gun.

This is what I would do:

1. make sure you have a story people can write about, a launch is usually not enough, some types of sites are interested in close fundraising (like tech crunch).

2. ensure you have the story down as easy to digest bullet points, as well as a standard press release (in case they ask for it) and a press pack.

3. make a list of all the publications / websites you want to feature in

4. find out the names and email addresses, twitter handles of each of the relevant journalists (look for people who have written about competitors or similar products)

5. If possible get the phone number of the journalist.

6. In my experience NOTHING beats calling up the journalist yourself, they're far more likely to listen to you if you call them than if you email/tweet them

7. See if you have any mutual contacts on LinkedIn or other networks, if so get introductions.

8. Otherwise, call if you can't call, email and tweet.

Happy to give you more specific help, ideas and support on a call.

BTW, I recently got coverage in two national newspapers for my own startup.