This has actually happened to me over the course of the past 3 years (I finished college and did not expect to advance in my career as quickly as I did).

The biggest difference for me was being able to afford a car. I was traveling by bus 1.5 hours each way because car insurance for young men in Canada can be insanely expensive (many of my friends pay $300-500/month). I was able to save up enough cash to buy a reliable 10 year old car, nothing fancy. This made the biggest difference because we could suddenly travel so much easier.

Then we moved into a bigger, nicer apartment that had 2 parking spots included. It's about 4 times the size of our old apartment, but it's only 30% more than our old apartment and it's around 25% of our take home pay (in a city where most people spend closer to 50% of the income on housing).

We spend more or less the same amount day to day, but we can now afford some travel, more in depth hobbies, etc. Right now we're saving for a mortgage, about 25% of our pay goes towards that. Whatever I have left at the end of the month goes into that savings account on top of the automatic withdrawals that come out of my account. I have two expensive hobbies that I get a lot of satisfaction out of, but I try to be as frugal as I can with those as well.