First, I want to say great plug-in.
Two things I like about your plug-in are:
1. The ability to set custom object types on posts and pages so that you are not just limited to the standard Article/Post object-type.
2. I also like the ability to manually set an image for posts types that do not have a Featured Image. This comes in particularly handy when your post contains a video but no Photos, for example: http://sportsandleisureband.com/videos/ OR http://sportsandleisureband.com/videos/sports-leisure-sunburn-live-on-lundi-gras-at-circle-bar-new-orleans-la/
What I would like to see in your plug-in:
1. The ability to associate your Open Graph data with a Facebook Application and/or Page:
<meta property='fb:app_id' content='FBAPPID' />
<meta property='fb:page_id' content='FBPAGEID' />
This is important if a user is going to eventually add an Activity Stream or similar OG Plug-In to the site.
2. The Post Description should auto-pull FIRST from the post excerpt OR All-In-On SEO OR WordPress SEO by Yoast (this could be an Option in the main plug-in settings), second from Post Content, third Manually Filled In.
3. The Post Title should have an option to auto-pull from the Post Title or one of the previously mentioned SEO plug-ins.
Those are my suggestions for now!