I've stayed at both and personally love the GF, but also like AKL. I, too, wouldn't stay @ AKL w/out savanna view - but w/ 2 boys the age of yours I suspect AKL may be a better fit. Will the GF courtyard pool be reopened by late Feb.? I thought it was supposed to reopen in March.
I second the Sanaa recommendation, but since you are going in Feb. plan on a meal during daylight hours (early dinner or lunch) so you are able to see the savanna animals better during your meal.