Honestly, if you want to give her something to treasure, why not write up 60 things that she has done for you or that you admire about her? They can be funny, touching, emotional, serious, goofy...anything. You can categorize them, or they can be random. Write them up, have 2 people proof them for you (2 fresh sets of eyes, you know?) and then figure out how to print them. You can take them to your local quick printer for ideas on printing and binding. You can order a hardcover book through places like Shutterfly - they provide templates and you can personalize it as you wish with photos or different layouts. It's pretty foolproof. You can give it a title, you can do a dedication, you can do a cover....and on and on. It's actually not all that expensive. We did one for someone's 95th bday - we called it "How Do We Love Thee? Let Us Count The Ways" and then we put in something about it totalling 95 things. (Feel free to steal the title - we appropriated it from Elizabeth Barrett Browning's famous sonnet! And, by the way, we didn't violate copyright laws!) You can include photos of her, of her and you, her with your family, even photos of any of those gifts you admire. Anything.
My husband and I each did a section, our son did a section, and then we had a 4th section that was our shared memories with the recipient. You can do it any way you want. My son sent the thing off but I think the book cost something like $40. Not bad at all! The more lead time you have, the less you have to spend on express shipping - although you can have it shipped to her instead of to you if you want.
It's a lovely keepsake and a treasure she will be able to look at any time. You're right - a gift card is fleeting, and she has everything she can buy herself. This, she can't buy. It's one of a kind.
If you don't want to do a printed book, you could do a scrapbook if you have enough stuff to fill it. We also did that for a milestone birthday for someone, with a big group of us each doing a double page spread with our thoughts about the person, and photos of her from youth to old age and everything in between. (Not that I think 60 is old age - I'm talking about what we did for someone's 90th.)
Some people get a chuckle out of the typical "60" things like an AARP membership card or a bottle of vodka and a bottle of prune juice. Some people hate that. So give thought to it.