La buena (Spanish fleur-de-lys tiara) and the tiara from the Dutch house diamond parure (probably in the largest incarnation) are indeed very probably for the Spanish-Dutch visit. The question more, which other Dutch ladies will attend, and what will they wear. Royal-Royal visits often mean 'all hands on deck', so probably Princesses Beatrix, Margriet, Laurentien. I don't think, that Amalia will already start state banquets yet, but who knows?
It's difficult to guess, because there are so many tiara available, but here's my guess:
Beatrix - antique pearl tiara
Margriet - Queen Emma's diamond tiara
Laurentien - the sapphire necklace tiara for the first time (hehe, this more of a hope than a guess)
As for Queen Mary, I think that she will wear the pearl poire tiara both in Sweden and Norway, and I fear that she won't wear the necklace. I think she'll introduce the emerald parure at the next New Year's Reception and leave the floral aigrette and will save the floral aigrette for next year, or so.