I was Accor Adv Plus member until last year.

This membership might not fit young family with 2 or more kids, most of the hotel room only have capacity for 2A and 1C

Also to note, their regular promo might be more attractive.. ie cash spend for each night in the hotel or 2nd room free ... If I recall correctly, you don't get extra disc for promo... the 10% disc is strictly base on room rate

Yes, pick the most expensive hotel and the free night is well worth it But beyond that point, it all depends on preference and circumstances.

For me, I don't dine in the hotel or uses their spa services and now I have 2 kids, most of their hotel required me to book 2 rooms ..... I prefer renting accommodation that allow 2A 2C. Also don't forget, this day lot of hotel provide free night when booking for 2 days +