I also think we should avoid the double if we can - maybe we can't. I have no insight on who would be best to take the defensive assignment on him. What I do know is that the most important thing will be to keep LeBron from penetrating. In that Washington series, he got inside virtually anytime he wanted it. That leads to lots of kick-outs to open shooters, FTs, and confidence-building, momentum-changing dunks by LeBron. His jump shot has vastly improved this year, which is part of the reason he is so tough. BUT, I'd much rather take my chances with LeBron shooting contested jumpers all day as opposed to him attacking the rim.
Also, the C's have to find a way to put a ton of pressure on LeBron to make him play defense. Wear him down, frustrate him, draw fouls on him, etc.