Soontobe. Hi, I'm with some on here and not too keen on the "decade presents".Personally I would prefer something for myself, like a nice piece of jewelry or perfume.
As far as the weekend being flat!!!! There seems to be enough of you to ensure that this will not be the case.
Have you any family movies from when you were kids and also of your sisters and your kids. Special photos!
You could have a movie/photographic afternoon with a selection of her favourite music playing in the background,(even some singalong) with all her family around her.This would create lovely memories, then at the end of the showing, present her with gifts and birthday cake with candles. Then all go out for super meal together.
This would be my perfect birthday. At 70, looking back, our greatest achievement is our lovely family.