Our school said it every morning regardless of grade. I stopped reciting it in 10th or 11th grade, but I was required to stand. Part of it was teenage rebellion, I won't lie, but there was more than that.
I do think the Pledge is harmful. Yeah, I think the under God thing is offensive, even though I am not an atheist or agnostic, but I would think that the Pledge is inappropriate even if that wasn't added to it.
Right around the time I stopped reciting the pledge, I read Dalton Trumbo's Johnny Got His Gun. What profoundly effected me wasn't the disturbing setting and plot of the book, but some of his preachy ramblings about war, symbols and how people get tricked into war without questioning. I don't think that all war is unjustified (neither did Trumbo as he stopped allowing his book to be published during WWII because it was being used by pro-fascist groups to rally against US involvement), but I think things like the pledge help blur the issue enough to make it more difficult for people to decide without relying upon "my country right or wrong". It also helps lead to the false dilemmas so artfully used to help characterise dissent to the second Iraq war (and the first one when you get down to it) as "unpatriotic". It's much easier to demonise someone who objects to a policy than to even listen to them.
When you recite the Pledge, you are allying with a symbol, not what that symbol is meant to represent. You are not promising to try to achieve liberty and justice for all, but to assert that this magical indivisible nation already has it. You are firmly stating that you will sacrifice ideals for this symbol ("which so many shed their blood for" which I was told when someone confronted me about my pledge abstention).
Even as "good Americans" we should realise that there are more important things than even loyalty to our country. I lied every school morning from K-10 because I really didn't believe or understand what I was saying. It isn't that important, especially looking back, but I remember it being a huge bone of contention with me during my last few years of school.
Re-reading this, it seems a bit teen angsty, but I still believe most of it. There are so many things that could be recited or discussed that would be more productive for American students or the US as a whole. It probably will seem a bit OTT for some of you, but it was a huge thing for me as a teen, and I took a lot of crap (small town) about it.