I faced a similar issue about a month ago, all standard luxury hotels in Paris were overpriced (for me) to book the 7 rooms that I needed for the family getaway weekend. (La reserve, as proposed above here and which we like, was also priced at about 1600 a room a night which didn't make sense needing so many rooms for 3 nights.)
At that time I made the following list of sub-luxe but still very nice hotels that could be an option for our family.St James 9,3 booking 4,7 tripadvisor

Madame Rêve 8,9 booking 4,5 tripadvisor

So Paris Hotel 9,1 booking 3,9 tripadvisor

Manolita Paris 9,6 booking 5 tripadvisor

Le Narcisse Blanc 9,2 booking 4,8 tripadvisor

Fauchon l'hotel 9,3 booking 4,5 tripadvisor

Hotel San Regis and Pavillion de la Reine where theoretical options as well but they didn't have 7 rooms available for the period that we had our weekend planned.
In general slh and lhw can be good sources for affordable but still nice hotels.
We ended up booking Le Narcisse Blanc at 700 a night a room for 6 rooms and 1200 a night for 1 suite, breakfast included