Hmm . . .
Why don't you try to find a place where you know you guys will be alone? If you can find such a place, then why not make him an exclusive party?
You can make him his favorite dinner dish. You can also adorn the place so that it will be intimate and romantic, as you say you want it to be. You can have a nice candle lit dinner, which is very traditional, but also very sweet.
Also, you can try your hand at writing him a poem of whatever you deem appropriate, and let him know what he means to you in this way. You can also recite this to him after dinner. (This can feed his artistic and intellectual hunger.

)
Then, after that is done, you can clear the table/get it out of the way, and play some music you'll both enjoy and dance. You know--drinks and dance.
Maybe something like that. Or maybe I just wish someone did something like that for me.