As a kid, the constant was a cake and a present, as in ONE, very rarely did we get more than one. We got to choose what we had for dinner, didn't go out unless it was a "special birthday", 10, 13, 16, etc. I only remember one party, maybe 5th or 6th grade where I had a bunch of kids from school come to a party. My mom liked it to be just family for celebrations like that.
As an adult, not a big deal unless it's a milestone. Went to New Orleans for my 40th, I'll be 50 next year and have my eye on a cruise, much rather have a trip than a party. It's in Oct. so I did spend one at F&W a few years ago as well. This year, will probably go to dinner with my BF and my DD15. I've hinted that I'm almost out of my favorite perfume so I'm hoping he gets that for me. I do have 2 coworkers who are also friends who share the same birthday week so we always make a point to go out for apps and drinks one night that week to celebrate the 3 of us.
My kids have had parties and also low key birthdays, never really any specific traditions, just whatever works that year. My DD turned 15 in Jan. so we spent her birthday weekend in Chicago seeing Hamilton, going to the aquarium and out to a very nice dinner, that was a very nice nice ($$) gift, will be hard to top it for 16 lol. It's a bummer because it's always freezing on her birthday so no outdoor parties ever.