This was posted on another thread a while back, but I really agree with the sentiments of YakMe when it comes to new blocks.
Also - if you could include a portcullis to go with the drawbridge that would be perfect.
Regarding PVP - would be nice if it was optional for people to destroy the work of others, but it is more difficult to do so with standard tools (Players can build catapults to smash down walls if they so intend, but even that takes time) -again optional.