How To Celebrate 90th and Other Milestone Birthdays

I'll be flying out to California soon to celebrate the 90th birthday of my dear Aunt Dot.  There's going to be a lunch in her honor but she doesn't want anyone to fuss over her.  To mark the occasion, I've written her a letter to let her know how much she means to me.  I included some specific examples of what I love and appreciate about her.  And I reminded her of some funny moments we've shared over the years.

But I have not purchased a gift yet.  After 90 years, she really has everything she needs plus I'd really rather DO something nice for her, instead of BUY her something.

Let me ask you dear listeners.  What are some ways to mark a big milestone birthday?  What gestures or outings have you appreciated on your big day?  Have you helped plan a celebration to mark a 70th, 80th, or 90th birthday?  What goes into making it a beautiful memorable day?