boyfriends birthday

so it's my boyfriends 18th birthday in a month, and I have no idea what to get him! 18 is a pretty significant birthday, and I want to get him something to show the significance! he won't give me any ideas; he said he would be more than happy with getting nothing but a planned out day spent with me, and that's what he wants, but what do I plan out? also, what do I buy him? his birthday is during spring break and since my 16th is the day after I want to plan a party of some sort for us the night of his birthday so it's for the morning of mine if you get what I'm saying? I just really don't know what to do! suggestions? please help!