Hee hee - I feel your pain. We had to move up from a queen size to a king size bed the first year 'cause our little guy was in with us so often. He stopped coming in when I weaned, though, at about 13-14 months. Now he only joins us when he's sick and wakes often during the night - we're too lazy to keep going to his room to comfort him. Happily, this has only happened 3 or 4 times in the past year and a half! If you've already weaned, try sitting with yours in his room with him in his bed, singing, patting, etc while he goes to sleep. Ours cried like crazy at first, but he was just mad that we weren't doing what he wanted us to. He wasn't alone, abandoned and neglected, he knew we were right there with him. (my husband and I did this together) If he wakes up at night, go to him, and repeat the singing and patting process. We'd agreed that if he cried for 15 minutes straight, we'd pick him up for 5, so he could calm down. This never happened in the middle of the night, though there were a number of times where my husband or I would go in and put a hand on him and reassure him that everything was ok. He always went back to sleep within 5 to 10 minutes. You may want to plan to spend a week of your vacation time on this, so you won't be all stressed about losing some sleep. You created the habit (I'm not criticizing, believe me, we did the same thing and I wouldn't do it differently with a second child - co-sleeping was a precious time in my life) so you owe it to your guy to help him break it with as little trauma as possible. Best wishes!
-L.