We are just back - my twelve-year-old grandson and myself. We had a wonderful time.
We travelled by Eurostar and stayed in a Best Western hotel in the Saint Cloud area - Best Western Auteuil Eiffel - for three nights. The weather was very hot and the air conditioning was not very effective but after the first night we were given a fan and slept well after that (my grandson slept like a log every night!). The people who worked there were terrific, very kind and helpful (even ironing my linen trousers and top for me). It had been newly decorated and was clean.
We could catch the 72 and the 22 buses outside the hotel to the Hotel de Ville. We had Paris Passes which were very convenient though we have worked out they actually cost more than paying separately for things would have done. If we had managed to get to the Musee d'Orsay (no time) and up to the top of Notre Dame (huge queues..) then it would have been a bargain.
We went to the top of the Eiffel Tower (as it turns out 3 hours after it had been struck by lightning!!), up the Arc de Triomphe, on the Bateaux Parisians, on the On/Off bus, to Notre Dame, the Pompidou Centre, the Louvre, the Orangerie, the Tuileries, Sacre Coeur, walked all the way down the Champs Elysees. We used buses a lot and the metro only a couple of times: once to go to the Catacombs - when we got there the wait in the queue was 2 to 3 hours and as they stop entries at 4 and it was already 2 we decided not to wait.
There is nothing I shan't do on my next trip, with my twelve-year-old granddaughter (assuming she wants to do these things) though I might try to find a hotel nearer the centre and I would certainly book early to ensure tickets for the Eiffel Tower, though as it turned out we didn't have to wait long.
At no stage did I feel anything but safe, I kept my bag very securely tucked under my arm and did not respond to any of the people with "petitions" who accost you. There are warnings about pickpockets everywhere.
Thank you all for the great advice. Let me have any more you have.