When my daughter is obviously tired but does not want to take a nap I have a strategy. I lay down on my bed and tell everyone to get out of my room. My two year old inevitably complains about it. I tell her I am tired and I need to leave so I can rest. She will then cry and point to my bed. Then I tell her she can lie down as long as she is quiet and does not disturb me. She then will cuddle up to me and usually falls asleep in less than a minute.
Sometimes I feel guilty about it, but works most of the time.
She is such a cutie.