When it comes to burning the flag or anything that could be considered offensive and highly insensitive to many people, it should be done away from public view, similar to laws that prohibit certain behavior around school zones.
I beleive it's important that we make bad behavior as uncool and unacceptable as we possibly can, and reduce the amount of agitation in public by the bad apples of society. I can list a bunch of behaviors that don't physically harm anyone, but if they were done in public, would have severe consequences for the 'agitator'.