Thank you Danny for your kind words. I think your husband will love it in Paris and it makes for such a brilliant surprise trip. There are several hotels around the Opera House. One of the best places to stay in Paris is the 9th district. We really liked it there, to be honest. It was clean and quiet.
So you can stay there for 3-4 nights. There are other hotels which cost around $100-150 per night or even less if booked in advance.
So we do think the 9th district is a great place to stay if you are looking for a couple in an elegant setting.