Transportation

I'm sorry Ed, but I can't offer too much, but since I have a long layover in Helsinki, I looked up this info a few days ago. It appears that the train is a great option, and it would take 5.5 hours. However, this would require the visa. If you travel by ferry to St. Petersburg, you can fall under the 72-hour visa free arrangement. I am sure the more experienced and knowledgeable travelers will add to this, but at least it's a start!
Happy travels!

Thanks very much.

Monique is right. If you only want to see St. Petersburg and not other parts of Russia, it's worth taking the ferry, because getting a visa is quite a hassle and quite expensive. If you do have to get a visa (which you will if you're staying more than 72 hours or if you arrive by any means other than that ferry or a cruise ship), here's information on the train: http://tinyurl.com/ar83knw

Harold - thank you for the information and your advice.