Maybe, forget about SPG hotels.
In Europe, there are many apartment style accommodations with kitchenette.
Those are usually cheaper than SPG hotels, especially category 4 or 5.
I know you want to use points to save money, but if the hotel requires two rooms or more points for suite, the apartment could be better deal for your family.
Also, you can cook in your room, too.
Europe is not a cheap place for breakfast, lunch and dinner.
So you can save a lot of money.