Work Invite Protocol

From your description I wouldn't invite your boss. I don't think it is necessary at all.
I went to look at a few before my FI told me about him and was completely unimpressed with the work I saw and the prices!

I chose to send wedding announcements to the co-workers I didn't invite to the wedding. I just printed them on the computer...simple, easy, etc. This way, they were thought of and included in the celebration without 'obligating' them to attend nor a gift...and they were appreciative of the kind thought.