If you don't ask, the answer is always no! It's no skin off the front desk employees' noses to give you an upgrade, so it's not rude to ask.
Okay, this is not really true. Lots of folks have reported getting upgrades without asking. It happens. Indeed, that's normally how it happens.
Second, there is a way to ask about this that's not tacky, and a way that is tacky. I think it's tacky to ask for a free upgrade, but there's nothing wrong with asking how much an upgrade would cost.
I've said many times, it never hurts to treat various employees you meet politely and kindly. Lots of time, at WDW and others, we've been given freebies just for being polite and for being a repeat customer.
If I am inclined to ask about a room upgrade not that often), then I ask what the price difference is. Sometimes, it's only a few dollars. You may find that to be true for you.
I'll never forget one trip I had where I planned to stay at ASMu on arrival night. Just after arriving, there was a sudden downpour. Suddenly, trudging to a room on the back of the property in the pouring rain with luggage, was less than appealing. Turns out, an upgraded room was only ten dollars!
Last minute cancelations also happen- so maybe when you booked- the room category above yours was not available (or not available withthe discount you booked) but now it is (for the difference in price). So like the difference between a "Standard" view and the next category up might only be $5 a night- even at the deluxes!
Sometimes upgrading is more than I want to pay, and that's okay too.
I've been to WDW many times....once in a great while we get free upgrades without saying anything at all.
Either way, I'm sure your stay at GF will be very enjoyable. I often stay at deluxes in the least expensive rooms, and I'm often surprised by how nice they turn out to be.