Mark Kleiman argues against trying to impeach Bush and Cheney. He is very convincing, although, in a way, he proves too much, showing it would be bad to impeach just one of them and neither will be impeached. He proposes a plan B which is very tough, confrontational and smart.
Anyway, I want to propose plan C for crazy. The problem with trying to impeach Bush and Cheney is that it would make Pelosi President. I think she would be a fine president, but impeachment requires Republican Votes in the Senate and no way are they going to give the White House to the Democrats. Plan C involves electing as speaker a reasonable, honest, intelligent Republican Congressman after the House sends the bill of impeachment to the Senate. That way the Senate (including the necessary 16 Republicans and Lieberman) could put a reasonable Republican in the White House.
The reason Plan C is crazy is that it assumes the existence of a reasonable, honest, intelligent Republican Congressman.