Fred and Barbara Fields are seasoned travellers and have written several trip reports about the places they have visited - including St. Petersburg (as part of a wider Eastern European tour in 2011).
I think it is interesting and well illustrated with representative photos, and it gives a good indication of what can be expected when visiting Saint Petersburg.
You can read the report on their website http://www.frf.com/russia or download a PDF version of their Russia, Eastern Europe tour trip report to read at your leisure.
Rock & Joan O'Keefe, an Australian couple, visited St. Petersburg in 2010. The sent a series of emails to family and friends telling them about their travels in different cities and countries. This is their account of the time they spent here Saint Petersburg Trip Report (Aug 18, 2010)
(note this file is in PDF format).
Ruth and Terry Wilson have created this interesting slideshow of Catherine Palace, which they visited on an excursion with me in 2011.
You can also view the slideshow on YouTube or download the Catherine Palace Slideshow (in FLV format to watch offline on your computer).