Will requesting a busy week make it more likely it won't be approved? Ahhhh, what would you do?
We were told to give them 3 different dates that were between the months of October-May (no summer months as it's too hot), no school holidays, and no week of any holiday. This, of course, is our wish projects (Montana Hope Project) policy. The travel during no holidays is, I think, a way they can get cheaper flights out of here (MT). So when we were called in September, I gave her 3 dates, first week of December, last week of January, and first week of February. We wanted to go when it's freezing up here. They chose our first choice, December.
Another thing, a popular week may be harder to get into GKTW. Of course not everyone has the same spring break so you probably will be just fine. Our spring break is the first week of April.

It was a hard choice to say no to that offer, but we decided to stick to our original plan. I think with the special attention to Wish families - the crowds shouldn't be too much of a factor hopefully. 
When we went to Disney 2 yrs ago they had it on sale if you purchased it before your trip. We got some great pictures and we were actually chasing the photographers around to get every shot! They also give you a release so you can get photos printed at home. I did have to show this when I got them printed at Sams.