Here's some big differences:
- Your cars are a lot nicer than the cars back in the early 70s. They probably have power locks, power windows, air conditioning, surround sound, far more safety features (air bags are expensive) and maybe some nice features like heated seats.
- You, and your kids, probably have a bigger/nicer TV, DVD player, satellite/premium cable, and a game console.
- You have at least one computer at home - unless you post to Slashdot from work.
- Plus, you are paying tuition/housing for two kids in college - and college tuition increases have exceeded inflation for decades.
Really, if you wanted to be in that comfortable middle class like your dad, you would probably have to give up a lot of comforts they just didn't have back then - and it's a lot nicer to have air conditioning instead of a fan.
Also, you might want to recheck your definitions. I'm guessing that you are spending a lot of money that you don't have to if you are only living a "boring" middle-class life. Or, you might not realize what a middle-class life actually is. The middle class doesn't have everything they want, but they do have everything they need - plus a little left over for nice things on occasion.
Middle-class vacations back in the 70s was loading the family in the car and driving to visit relatives and staying with them to save costs. (Although camping was a good alternative.) Flying somewhere and staying in a hotel was definitely a sign of being upper-middle-class at the very least. Plus, do you buy designer clothes or buy "regular" brands? Middle-class is picking up your day-to-day clothes at Target or Walmart, not Macy's or a specialty store. Plus, the middle class does things like clip coupons, wait for sales or other things to stretch their dollar.