Lol at the jazz flute. If you can pull it off by all means go for it! =)
On a more serious note, if he really just wants to spend time, then just spend time together. Focus some attention and creativity on some little things to make the day special (e.g. going for dinner and secretly asking the waiter to bring a birthday cake at the end of the meal as a surprise, on the more stereotypical end, or just get creative!).
Just make the day about him, and use the time to express your appreciation for the time that the two of you have spent together in the past year. Have a good one. =)