It sounds like your wife is taking pride in her appearance, is gaining confidence and feeling more sexy and beautiful and that is a wonderful thing compared to the opposite of that.
It sounds like she is being respectful of your hard work, looking for bargains... but it also seems like maybe she wants to 'live a little' to taste the 'good life' here and there... and I can't say I know any woman that wouldn't appreciate being able to do that from time to time.
In many women lives a little girl that dreamed of being a princess. A pair of high end shoes, an exotic lotion etc... are little tastes of that.
As long as she is not pushing you guys to live beyond your means and isn't being over indulgent I wouldn't worry with this behavior.
A lot of women are realizing ( a good thing) that they can be sexy and beautiful at any age -- that they need'nt put on a moo-moo frock and let their hair go white when they hit a certain age.
I think it sounds like you are a lucky man, in my opinion... to have a lovely lady in your life that is getting more beautiful with every year.
If you worry about your daughter being over indulged... talk to your wife about it so that you guys can set some bounderies on just how much you cater to your teenagers every whim to fit in with the stylish crowd at school.
With shows like the 'hills' etc.. younger girls are exposed to high end fashion and brand names and feel like to be cool and popular they should be in the latest designer duds. Its normal. Even girls from families that can't afford it are trying their best to 'look the part'.
If your wife was distancing herself from you, spending in a way thats wreaking havoc on your finances -- that would be a reason to worry.
But her wanting to flirt with a lifestyle thats within your means is nothing to worry about as long as she is still grounded.