Lorri -- I used Uber yesterday from the airport. They have fixed rates to/from Paris (scroll down the page). 50€ to/from Paris/CDG to the Rive Gauche, where you're staying. Scroll down on the page to see the rates:
https://www.uber.com/cities/paris
It worked pretty well - I opened my Uber app while still in the terminal and could see that there were plenty of Ubers around. I knew that they would NOT be at the taxi stand, so I was curious about how it would work. In fact, it turns out that the software that the drivers are using pinpoints pretty much EXACTLY where you are at the airport (b/c CDG is so big, this is important, the terminals can be quite far flung). For me of course it worked pretty easily, as the guy called me and we talked about which entrance porte/gate to meet at (all the entrances/exits at the airport are numbered in order to facilitate this). But he said that if it were a non-French-speaking client, they would send a text. Just remember that it will basically say "Porte 8" or similar and that means the driver will meet you outside Door #8.
He handled all my (very heavy) bags with aplomb (no judgment people, I was returning to Paris from my once-yearly trip to the States, a girl has to bring in her peanut butter somehow!! hahaha). For me the 45€ (the cost to the right bank, where I live) was probably a little MORE than what a taxi would have cost on Sunday morning, but to think that's all I would pay even if I were coming in during a rush hour Monday, now that would REALLY be worth it.
Of course, your phone has to be able to accept international texts in order to get the driver/license plate information, so make sure that you're set up for that.
The one thing I don't know is how you would request a larger vehicle. It's pretty easy when you arrive at the taxi stand -- basically you'll wait until an appropriately-sized vehicle comes, and your family will get in that. But a family of 4 with luggage might have had difficulty fitting in the sedan I had yesterday.
if you have any other questions, let me know!
Kim