If you need more information about Guest Assistance Cards, there is a section in post #6 of the disABILITIES FAQs thread.
as a side note, i dont know if you have used a GAC before at disney, but you may find it not entirely helpful. There is no GAC to skip lines, and the distance walked from entrance to ride is the same with or without a GAC, generally... I am sure others here can give you more info!
Yes, that is an important point. The distance is usually going to be roughly similar. With a GAC, you will be able to avoid stairs and you will also be able to board the attractions with moving walkways at the exit where the moving walkway can be slowed or stopped. But, the distance will be roughly the same, with or without the GAC.
Here are some links that might be helpful:
Thread about attractions with no place to sit while waiting (includes info about distances walked in line).
Estimates of walking distances per day at WDW.
Past thread about attractions with moving walkways - it is an older thread, but the information is still valid.
I only need them to stop/slowdown the moving walkways and I can't do stairs. It is getting in and out of rides that will be tricky. The stairs on the busses will be hard but I think I can handle it for the time that we are there.
The older buses have stairs, but there are a large number of buses that are newer and have ramped entrances at the front for getting on and the rear for getting off. You always have the option to wait a bit longer to get a bus without stairs.
If you are using Disney's Magical Express to get to and from the airport, be aware that there is a steep flight of stairs to get on and off. Post # 16, page 2 of the disABILITIES FAQs thread includes a picture of the DME bus stairs. The flight of stairs is higher than average on those buses because there is luggage storage underneath the seating area.
I don't mind standing as long as I haven't pulled a muscle but the Dr. gave me stuff for that too just in case. The NSAIDS should help with my knees as long as I avoid stairs when possible. I am sure by the end I'll need my knee supports and maybe even my cane but I don't like using them unless I have to.
I'm sure you already know this, but (as I nurse) I fell like I should remind you that anything you do to avoid or relieve pain will be more effective if you use it before you are in pain. If you keep going until you are in pain to use your aids, it will be too late.
And to answer your original question:
Some people have an answer ready like - "IF you want one, you have to take the bad knees that came with this one."
Some people keep their GAC out there where it is visible. That is likely to get more attention and more comments.
Our youngest DD uses a wheelchair, but has additional needs that make a GAC necessary.
Most people don't even see her GAC because I get it out only when we need it for an attraction. I keep it in a pocket of my purse where I can get it out quickly to show CMs and pop it back in just as quickly.
When we don't need it for an attraction, it stays in my purse.
We have not gotten any comments about the GAC. We have gotten comments about DD's wheelchair - even though it is a very obvious custom wheelchair with a special seat back and cushion and extra straps to keep her feet in place. We have seldom gotten comments about need, but the one that sticks in my head was when we were at Epcot in Germany and I was sitting with her on a bench while my DH went to get her a pretzel. She was sitting on the bench with her legs crossed when 2 guys came by and one said to the other, "There's one of those cheaters who just get a wheelchair to go ahead in line." He did not know us and obviously had not used a wheelchair because he would have known that having one doesn't get you ahead in line.
He was just assuming that because she was not in the wheelchair, that meant she didn't need it. What he had not seen was that we had to lift her onto the bench because she can't transfer by herself and she can't even cross her legs by herself once she is sitting.
Interestingly, the most 'positive' comments/attention we ever got was one trip when I had tripped the night before our WDW trip - I was walking with DD and her legs scissored and got tangled in mine. We both fell, but I managed to turn and take the majority of the damage. She ended up with a black eye and a bruise on her cheek. I ended up with a badly bruised shoulder and arm. I wanted to just become invisible because I felt embarrassed and guilty about our injuries. It took a while for me to figure out, but it turned out that people thought our injuries (and her wheelchair) were the result of a car accident! I don't know why, but one person asked me if anyone else had been in the car with us and how badly they were injured. So, you never know what people will come up with.
There are many more good experiences than bad ones, but the bad ones stick in your head. Remember, whatever they say, you know what your needs are and you are the only person whose opinion matters.