We just got back from Paris. I was looking for room with 2 double beds too because we have a 12 years old. But pretty much all the rooms with 2 beds are 2 twin beds. We ended up just getting 2 rooms.
As for transportation, we used Uber everywhere in Paris. We tried Taxi twice. First time it was just a few € more than Uber. The 2nd time, I think we got the "tourist" special as they charged a €7 fee on top of the meter. I think it was like €17 to go about 1.2 mile. On the way back (same route), it was about €7 on Uber. The hotel was trying to give us direction on which subway line to take, but just about everywhere we want to go, it involved changing line. With the 3 of us, I don't think it will save much on subway on such short distance travel.... just increase travel time. We are from LA and used to driving everywhere.. I guess people from New York will think differently.