I'm just curious why you would prefer a deluxe savannah view room? If I had booked a standard savannah view and was offered a free upgrade to a deluxe savannah view, I would decline the offer. The deluxe rooms are on higher floors and I personally prefer the viewing experience on the lower floors because they put you closer to the animals. The deluxe rooms are four feet longer, but the extra space isn't that noticeable really (unless you have a fifth person in the room!) So, I'm just curious why you are hoping for this sort of upgrade.
The only differance between these two room catagories is the size of the room. The the deluxe view room is a little bigger then the regular savanna view room. The view itself is not that different other than all of the deluxe rooms being on the fifth floor.
A friend of mine recently returned from a business meeting at the AKL. She had a deluxe savanna view and told me that I should try to get it. She personally liked the extra space. This is really the only reason I asked the question. However, from the comments posted, it doesn't sound like it's anything extra special other than the space so I'll be happy either way. Looking at the animals from a lower view does sound better though!
Personally, I would rather go for a standard view with the hopes of getting the savanna view upgrade but because this trip is for my husband, and because he doesn't want to look at a parking space, I'll splurge for the savanna view.