RE: HOW do I get DS to sleep in his new "big boy" bed???
I wuld try and let him decide to use the bed on his own. With my DD, we set up the bed, and I then moved all her toys and stuff into that room and we played in there, so it was fun. I kept asking her if she wanted to sleep there and she kept saying no, no, no... After a week or so, she said yes to sleeping there and she slept great. THEN we traveled and she didn't want to go back on the bed after that. But if we had not been traveling, I think it would have gone smoothly. We have since gotten her back in the bed and she's been doing great in it.
If he's sleeping with you, it may be a bit harder to transition him, but I would still try and take it slowly. Talk up the whole "big boy" aspect, but don't create any pressure.
Good luck!
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)