Charlie said, "I have been told several times that the best selling tours of theirs are their 7 day tours so that certainly influenc[es] their offerings."
Our first RS tour was to Istanbul for 7 days. I'm thinking one of the attractions of the 7-day tours could be the fact that you sleep in the same place and concentrate on it and its immediate environs.
I'd be very interested in a longer, 3-4 week, tour that is designed around a similar concentration on specific locations.
That would probably not be of interest to some, but it would definitely be better than trying to string 3-4 week long tours together. Not that there are many options for that since currently there are only 4 7-day tours listed: London, Paris, Rome, Istanbul.
I've enjoyed all the RS tours I've taken, but it seems to me that all the 5 other tours I've taken after that first one in Istanbul have tried to cram too much stuff into their roughly 2-week itineraries.
In fact, as I look over the current list of tours and itineraries, adding 1 single day to make 8 instead of 7 increases the number of places to sleep and makes the time in each place shorter.
To sort of quote Silva (Javier Bardem) in Skyfall: Do you see what comes of all this running around? It's exhausting! Relax. You need to relax...