Very thoughtful as usual, roach.
Where I disagree with you is on your comparison of our system to the brit parliamentary system. I would argue ours is the more democratic and provides better safeguards to protect the public interest for two reasons - the separation of powers between the legislative and executive functions and the codification of the term of office of the chief executive.
The british PM is in effect both the leader of the majority party in the parliament and the chief executive. His/her party controls both branches (or the functionality of both branches), making impartial oversight of the actions of the executive by the legislature far more difficult to ensure on an objective, non-partisan basis.
The term of the PM is also not set by law, but determined by the Crown, who disolves the parliment, generally at the request of the PM, who will make that request at the time most advantageous for his/her reelection or the election of a successor from his/her party.
On a side note regarding responsiblity for whom we elect, I didnt vote for Bush and I have no Senators and no voting representative in the House, so dont blame me
edit:
There is one feature of the Brit parliamentary system I would love to see us copy -
Prime Minister's Questions, where the PM appears weekly in the parliament to answer questions from members of all parties. It forces the PM to defend his/her positions on the "issues of the day" providing at least some accountable for his/her actions.