Sometimes is developmental, sometimes is teething but i have found this age to be particularly tough with spirited ones (my own case). I had pretty much what you describe at the same time and ended up 2 months later with 3 brand new molars (the first one popped at 13 mo with less fuss). How did i survive? teething meds 30 mins before each bedtime (on particularly bad days i even gave tylenol+motrin+homeopathic remedy at the same time... be sure to check with your ped first). I restorted to wi/wo after 2 week period of gentle removal plan (which i had to do because of accidental parenting, which is not your case). I also talked my lo a lot during the day about nap/bedtimes, we played to put stuffed animals to bed (we even put the fan to bed
) and he left the room and see that monkey/teddy/fan were ok, just as he was when i put him to bed and left. I made him put me to bed and played all that jazz until i eventually"convinced!" him that it was ok to go to bed. He never was like that as ababy, he'd be happy to be in his crib, but at 15-16 mo he just went crazy LOL...
I also found that a looong wind down (up to 20 mins) would help us too. During that wind down he would wave bye bye to everyone/everything (family, cleaning lady, trees, cats... you get the idea)... up till now he knows that everyone goes to nap at the same time he does and he's more happy with that.
So with spirited toddlers is more about letting them find a way to do things (or at least make them beleive it's their choice and their way
) and that will lead you to smoother bedtimes. HTH and that i made some sense!