It's hard to plan a birthday party for a 60 year old. First off, they've already had 59 birthdays so it's going to be hard to come up with something original and they might not actually be happy at reaching 60!
Don't let that put you off though. It's a significant milestone, which should be celebrated and with a bit of thought and planning you'll be able to come up with a birthday party they'll love.
First of all, think about the sort of things they are interested in, or they are known for. It could be a hobby or pastime, their career or just something like their sense of humor. It can be something as specific as an old song they love, or as general as stamp collecting or knitting. You don't have to be bound by this, but it makes it a nice touch to incorporate it into the general theme of the party. So it their favorite movie is "Titanic" you could play the soundtrack while eating for instance.
If it's to be a formal dinner then you could do things with a black and white theme. The guests can wear black and white outfits and you could display some old black and white photos of them or even back and white videos or movies. If you want to go all out, how about using that "Titanic" theme?
If they are into movies you could actually have a red carpet at the venue and perhaps even give out some spoof awards to the guests, and of course, the person of honor.
Casino night is always fun. You can play poker, roulette or slots and have waiters serve drinks and appetizers. You can hire some people to be dealers/croupiers.
How about a spa party? You can rent a room at a spa and have massages and various treatments with a group of girlfriends.
If they are as young as they feel, a karaoke night is always good for a laugh. Another set of themes could be Mardi Gras, carnival or fiesta complete with costumes.
To make the party more memorable, get someone to be a photographer and take lots of pictures, or have disposable cameras on all the tables. You can then present them with a scrapbook afterwards, along with a guest book from the party, that they will treasure always.