My husband and I took our 6 year old twins to Blue Man Group this afternoon.  It was great!  We had seats right in the middle at the top row of the mezzanine, which gave a great view.  The view was only improved by the fact that the total ticket cost was only $98 for the 4 of us, including fees!
My favorite part had to be the dance party at the end, where we held the girls up to stand on the chairs in front of us to shake, well, various euphemisms for bottom were employed.
Unfortunately there was no photography in the theater, so we didn't get to take any snaps of the monsters with the blue guys, but given their age they will probably remember pretty well.
This really brings to mind what I was reading in "Happy Money" which discussed the value of spending money on experiences, rather than objects.  I suppose it also met the principal of pay now, enjoy later, since our tickets were purchased many weeks ago.  I suppose it also counts under spending on others, and experiencing it with them, a la the Starbucks gift card experiments in the book.