Back to Sapper and BQ's debate:
First of all, it needs to be noted that the Overland Campaign was a campaign, as opposed to a battle. A campaign is a series of battles and movements designed to achieve a strategic objective.
The way I see it, Lee had two strategic objectives:
1. Preserve his army
2. Cause Lincoln to lose the 1864 election. A McClellan presidency was about the only way the South was going to get out of the war as an independent country.
Lee was partially able to achieve the first goal. He was able to preserve his army as an effective fighting force, but it was no longer a useful force, because he was pretty much trapped in Petersburg.
Probably the only way Lee could have achieved the second goal would have been to defeat Grant the way he had defeated the Army of the Potomac in previous years - smack them around hard enough that the army goes back into camp to regroup and try to figure out a new plan. Grant did make some mistakes during the campaign - North Anna and Cold Harbor - but Lee was unable to take advantage of them.
Grant wasn't able to achieve his main strategic objective - the destruction of Lee's army - but he did hurt it badly, and was able to pen Lee up in Petersburg, while Sherman secured the election for Lincoln by capturing Atlanta.
As far as the contention that Lee was "obsessed" with defending Richmond, he didn't really have a choice, for both political and logistical reasons. On the political side, the fall of Richmond would have almost certainly handed the 1864 election to Lincoln, as well as being a major blow to the internal political cohesion of the CSA.
On the logistical side, all of the rail lines, and thus Lee's supplies, ran through Richmond. Guerillas can exist without major supply lines, but a field army can't, unless they want to strip the countryside around them. Lee had no desire to leave Virginia looking like Germany after the 30 Years War. Without Richmond, Lee's only option would have been to retreat westward along the rail line (as he tried to do after Five Forks), where he would have been ultimately trapped anyway.
Lee probably did the best he could with the hand he was dealt. He had one brief opening to possibly stem the tide - at North Anna - but he wasn't able to take advantage.
OTOH, if Grant hadn't been saddled with the political necessity of leaving Butler in command of the Army of the James, and had been able to put, say, Sheridan or maybe Hancock in charge there, the whole thing might have been over in the spring.
