Hi! I didn't realize I had posted anything! There is an 18 month Sleep Regression thread here somewhere. I will try to find the link.
My son also all of a sudden started resisting bedtime. He is spirited and I thought it might be the stimulation of a bath, which he loves, right before bed time. Now we bathe him during the day. We used to do bath, Pj's/massage, bed. I also thought it might have to do with SA. So now we do PJ's/massage and then he sits on mine or DH's lap and we read books with him until bedtime, usually 15 min. I figured this gave him the chance to have physical contact with us right before bed. It seems to be working...most of the time!