I Believe We Have Found Our Sleep Solution...

First I would like to say thank you to everyone who responded. It was a great help to us and gave us a lot of good things to try.
This seems to be the solution that works for us: I had Tim go into the attic and bring down our toddler bed. He had to re-assemble it, so Sophia watched him work on it. I told her that it was her bed and I saw that she was concerned and her eyes watered up a bit. I told her to come with me.
I took her upstairs to my room and I pointed to my bed and I said "Momma's bed". Then I pointed to the floor by my bed and said "Sophia's bed". I said this three times and I knew she understood what I was saying to her.
When we went back downstairs, she pointed to her bed and then pointed upstairs and I said "Yes, Sophia's bed upstairs with Momma's bed", and she smiled.
We took the bed upstairs and put it by our bed. She climbed right in. I did some e-mail work and read some blogs for a while and she was sound asleep in 30 minutes. Tonight is our 3rd night of her successfully going to sleep.
She does not have night terrors, she sleeps very peacefully, it was just finding a way for her to get to sleep that she was comfortable with and I think we have found it.
I'll keep you posted if we have any future hiccups.