Has anyone taken this tour and then continued on to Moscow afterwards? If so, what were your thoughts about that - was it easy to set up the extension to Moscow (and if so who did you use to make the arrangements and did you take the train?), and how did you arrange local guides or tours? I'm traveling solo so want to do some research beforehand - really want to include a couple of days in Moscow after the tour ends. Your input will be much appreciated!
I didn't go on a Rick Steves tour, but I'll address the transit. From St. Petersburg to Moscow, you want either the overnight sleeper train (the fancy ones are very nice), or the fast day train (under four hours on very spiffy new trains). You do not want to fly.
Here are details on the various train options and how to book them: https://www.seat61.com/Russia-trains.htm
Moscow remains a highlight of my years of travel! It has been nearly 10 years but at the time I used Firebird/Travel All Russia and if they still exist and still have favorable reviews they were just excellent and handled everything (although I do remember asking to change the Moscow hotel from the one the company initially booked). The private escorted tour with their guide was a boon for seeing the subway station and Lenin's tomb, but the rest was solo. The fancy overnight train to St. Petersurg was like being on the Orient Express ( sans murder🙃). We went on to tour the Golden Triangle region for wooden architecture. St. Petersburg was easy to tour on my own.
We went on a guided tour using express to russia as the tour company. We were very ,very happy with everything. expresstorussia.com
While we booked the entire tour (hotels, train and sightseeing), others on our tour joined us for just parts . Yulia was very helpful. As others have said, use the fast train . You will love Moscow.
You will enjoy your time in Moscow. In addition to the Kremlin, which is beautiful, there are several world class art museums.
I did the high speed train from MOS-St Pete last summer and it was excellent. On-line reservations was easy and Uber's are everywhere in MOS.
I booked four separate day tours in MOS through Viator and all worked out wonderfully well.
I went to Moscow after a Baltic cruise for four days and really enjoyed it. We used Happy Moscow Tours. I believe they only do walking tours using the subway but they were very affordable and I would recommend them.
I'll second the fast train. Was well worth it. I believe someone posted the link above.