I'm too old (33). Not solely because I'm allergic to the cigarette smoke, and it leaves my ears ringing for hours and forces me to scream just to talk to anyone, but I find that the only folks I see in places like that anymore are the "recently-turned-21" college set who are still excited about such things.
Drunkenness is pretty old hat, though I've been known to get tipsy in the privacy of my own home on a coupla glasses of red wine once every blue moon.

Klutz that I am, it's better for everyone that I don't dance. Instead, I'm the one standing in the corner with a drink in my hand and a captive audience of 3 or 4, cutting up about people's hair and pants, my beagle or my kids....
My biggest issue is, I have absolutely nothing in common with people who club, and no real reason to be there. They're trolling for meat, I'm happily married. They stay out till 3am with no problem, I have to have my 8 hours before I can go to work. They can wear crazy outfits, but I can't waste money on frivolities I won't use regularly and am too tubby to wear "cool" clothes. They (with no kids to take care of) slam down twenties and buy rounds of drinks, while I have to make a drink last an hour and a half because I'm watching money. They are happy to be there...I look at my watch and think of the hundred or so other ways I need to be spending my time instead (cleaning, writing to make that magazine deadline, teaching my son to read, sewing new drapes for the living room...you get the idea).
If you have fun there, and feel comfortable, go for it no matter how old you are. Especially in your case, though...aren't you a stay-at-home mom? You NEED to get out and go crazy. So do it. But please bag the sensible blouse.
This old bat goes to coffee shops and movie theaters with her friends.
