I found this thread pretty interesting. I went to Disney on my honeymoon, and this is only relevant because we happened to be there on gay and lesbian weekend. I never knew they had such a thing but they were all wearing the same red shirts for a few days of our trip. I bring this up because this is the only time I have ever really noticed any gay people at Disney. My last 2 trips I went solo and I am a people watcher. I'll just sit on a bench and watch people for a bit while I am resting my feet. I never noticed any gay people holding hands. So, the only time I have seen it was our honeymoon. Clearly, there were a lot of gay people holding hands that weekend. We didn't think twice about it and this was in 1998. People seem more accepting now than then.
There were 2 incidents that stood out. I think the fact that you care enough to ask shows you will do whatever you do tastefully so you won't be apart of stories like these.
1. We were walking down Main Street and I looked to my right. There was a woman who had to be 6'6" and she was dressed like a prostitute. Clearly she stood out amongst the crowd. As if that wasn't bad enough she and her girlfriend started sticking their tongues in each other's throats. We didn't have kids at the time but I remember saying something to the affect of, that's real nice to do with all the kids around. (I would say the same thing if it was a man and a woman. It just isn't appropriate in that setting to the degree to which they were doing it)
2. We were on the Jungle Cruise ride. We were all packed pretty tight. I happen to have social anxiety disorder so I DO NOT like when strange people touch me. Well, there was a guy sitting next to me with one of the red shirts on that indicated he was part of gay and lesbian weekend. He kept moving his leg to touch mine. (On top of not liking strange people touching me, it was 105' and VERY humid out so I was sticky and sweaty anyway). Each time I moved my leg further away. After about 4 times I realized he was doing it on purpose. I finally said to my wife, loud enough that he could hear me, that if he touched me again I was throwing him over into the water. Surprisingly his leg moved back and he never touched me again.
I share these stories because I wanted to point out that the people who were acting respectfully didn't stand out to me. It was the ones who were going out of their way to get attention or make people uncomfortable that stood out.
While I have 4 small kids now, and like it was said earlier, wouldn't want to explain the differences in sexual preference right now, I also don't think my kids would even notice hand holding because they'd be so in awe of Disney. Now, they might notice a 6'6" woman dressed like a prostitute who was chewing on her girlfriend's face. That would bother me, but I still wouldn't say anything to them.
I hope you go and have the greatest time. Hold hands and if somebody does look at you the wrong way chalk it up to them being ignorant and keep on moving. Life is too short to worry about what people think.