Savings using Airmiles

Hi all,
We are off to Orlando next year, 25th April 2015, and I have a some airmiles left over from previous trips. We are 2 adults and 1 child (3 years old) travelling together. I could potentially have enough airmiles to do one of the following options:-
3 miles plus money premium economy flights
1 adult companion premium economy flight (paying for the other adult and child)
1 upgrade from Economy to Premium Economy (paying for the other adult and child in PE).
I know it's hard to predict with the changing prices depending on time of year etc, and how far it is in advance, but does anyone know roughly how much I would save with each option?
Thanks
We are off to Orlando next year, 25th April 2015, and I have a some airmiles left over from previous trips. We are 2 adults and 1 child (3 years old) travelling together. I could potentially have enough airmiles to do one of the following options:-
3 miles plus money premium economy flights
1 adult companion premium economy flight (paying for the other adult and child)
1 upgrade from Economy to Premium Economy (paying for the other adult and child in PE).
I know it's hard to predict with the changing prices depending on time of year etc, and how far it is in advance, but does anyone know roughly how much I would save with each option?
Thanks