Hi Went to Paris for 4 days in July 2011 and found the Paris pas useful though it looks a bit expensive but it is really not. I could use the open bus for one day only but still found it worth spending in Pass.
I visited Paris for 2 days and Disneyland for next 2 days. I found 2 days in Paris are not enough if you wish to visit many places.
I planned my tour myself, Getting Visa was easy and took 4 days, booked Eurostar tickets and stay for 4 nights in Bry-Sur-Marne. Paris Metro trains are easy to understand and has very good reach and frequency.
Overall a family of 4; One 7 Year and other 2 Year old spent around £ 1400 excluding Visa .
All the best
Pranay