Hi there! Who do you think Elena wanted to choose before chosing her grandfather to dance with her?
I think Francisco was her first choice from the beginning, and if she didn't choose Francisco she probably would have chosen Isabel or Luisa. (Or possibly Esteban, but I feel like she probably decided who she wanted to dance with long before she had forgiven him).
Being crowned was a very important moment for Elena and while she cares about both her friends and family, she just gave her friends job promotions, which means she'll probably get to see them all for work-related things. But she probably won't get to see her family quite as much being Queen, so it was quite a nice gesture dancing her Abuelo instead of one of them
And even if none of her family members were there, I don't think she would have chosen Mateo, Gabe, or Naomi for a very certain reason. You see, in the song “Fit to be Queen” Gabe & Mateo both seem very keen about dancing with her. But the thing is whether you believe that either of them or just one of them or neither of them have a crush on her, the fact is they both wanted to dance with her. And they seem to view her choice as a choice between the 2 of them (when it wasn't).
It seemed to me like a resurgence of their rivalry from "Party of a Lifetime," where they were fighting over who was her "best" best friend. And I know they've fought with each other about other things since that episode but never about how much Elena liked them. I mean Elena just cringed away from both of them and put their hands together instead of holding either one of them. Because whether you believe she has a crush on either of them or neither of them, she recognizes this could become a point of contention between them.
If Elena had chosen Naomi, Gabe and Mateo could possibly have also taken that personally and added Naomi to their rivalry. (Don't get me wrong I don't think that they would be annoyed about it forever, but they might make a rash decision in the short term because of it.)
I do Headcanon that Elena probably danced with all 3 of them at some point during the coronation. It's just that since the “most important” dance was the first dance, she dedicated that one to her family instead.