This is why we watch the parade in Frontierland. It is still bad, but not nearly as bad as Main Street. For a few years if we were in the parks we stayed to see the parade, but did not make it a must do kind of thing because it is so stressful. Now that ds is 5 we are going to make sure we see a few of them.
I am kinda lucky in a way because my dh is very tall & bulky (6'8 & 300lbs). He is as kind and gentle as can be, but most ppls impression of him (because of his looks) is that he is mean. This means, once we find out spot it is ours. No one gets pushy or elbowy etc. I mean jeez, its me they would have to worry about, all 4'11" of me, not my dh.
We dont mind sharing a spot with a younger child if the family asks or even if they don't & we know the child can't see or would like to sit down we invite them. DH puts my ds in his lap & I scoot over. Waa Laa another spot or two (depending on age/size of child) has opened up.
I agree, more education in the park maps or at the entrance might help some ppl plan better. Other than that, a rude person is just that a rude person & no amount of planning will change that.