A good idea for romantic presentation of watch is to present it in a big box so he will not be able to tell what he is going to get by simply looking at the box.
Put the watch in a box, put that box in a bigger box and then put that one in an even bigger box. Wrap all of the boxes in nice paper, or leave them unwrapped and just wrap the biggest box. Alternatively, you can just put the watch in a very big box and fill it up with torn newspaper.
A scavenger hunt can be a very romantic thing to do.
You can make it as long as you want, meaning the hunt can only last for a day or you can spread it over several days. Leave the first note on his work computer or in his favorite coffee mug so he will surely find it. Make the steps easy to follow, and try to connect the clues to the gift that is waiting at the end. Do this by including words like time, ticking and other hints that can be connected to watches.
Have It Waiting
Ask him to meet you somewhere so he will not surprise you by coming home.
Put the watch on a spot where he will immediately see it when he comes through the door. You can also put the watch under a card so he won't see it until he picks it up to read it. Go meet him, and, when you come back, let him step in the room first to find his present.
Sticking to Classics
Grand romantic gestures can be sweet, but the most romantic thing you can do for your man is to be honest about how you feel about him.
Tell him you love him, how much he means to you and how spending time with him makes you happy. After you finish, give him his watch. You can do this over a romantic dinner or wherever else because, ultimately, it's not about the watch and how you present it but about the special relationship you have with your man.