Leave Startup with grace?

I am a CTO at a startup, but I am looking to move to a different position for a number of reasons. I would like to get my vested options and be sure that I am not screwed out of them. I may offer my services for consulting, since they might be a little lost. I am thinking a minimum per-month for consulting? Perhaps they should just convert my options for me? I don't want to hold them for ransom, but I want to get what I deserve as well. Opinions on a course of action?

thanks.