I think there is something to be said for being 'always' frugal in some area's, and allowing yourself a lifestyle that you are comfortable with in others.
I don't think I could ever bring myself to 'waste' money just for the sake of spending it - but I still allow myself and my family certain luxuries. Such as holidays, new funiture (just spent $3500 on a new lounge, and I must admit to being near apoletic while spending that much - but I had saved up my cash specifically for that purpose), movie nights, social events, etc.
We are still able to afford a good lifestyle and save money because I am very careful about where the money goes. If DH bought lunch at work everyday (like many of his collegues) that is about $50 a week that could be spent elsewhere. Instead he takes a tin of baked beans and a sandwich, or leftovers from dinner the night before - much healthier for him and much healthier for our budget.
When we have more then enough money to ever worry about running out, I am sure I will still be a bit of a tightwad about certain things. But then I guess growing up as an elder child of six children, living in housing commission and remembering eating pancakes, and scones for days on end because the only food in house was flour and eggs, has an impact upon a person. I remember my dad working 18hr days and my mum crying when because she had no money and no food to feed us. So I don't like waste.