Really LOVE both these names. I have loved Declan for a long time myself. It's not super popular where I'm at, but I, too, have seen/heard it on lists or suggested. I don't think however, that it will ever be as popular as the -aden names. As another person said, part of that popularity is that there can be multiple first syllables added to that ending. That's not easy with Declan!
My brothers name is James, so I would also really love to use Jameson as a fn or mn to honor him. I do REALLY like the sound and flow of Declan James, though. That way you'd get to use the name you've loved for a long time and honor a lot of important people at the same time.
Needless to say, I'm not much help with this one!
I love Declan and Jameson; I have considered both names.
I don't see Declan getting super popular, but it does fit into two of the current trends -- names that end in the "en" sound and Irish names. Also, someone pointed out to me that it could be read as Da Clan/Klan. But honestly, I still love it. I don't think that would be a problem except maybe a little teasing.
I also love Jameson. My husband's name is James, too! I think Jameson could get popular because everyone loves James, it ends in the "en" sound, and it's a surname name (which are trendy). But, if it's a middle name, that's probably not a concern to you anyway.
Great names! Good luck!
Declan James is a great name! I love Declan, hopefully it won't become too trendy. The only place I ever hear that name is here, so I think that is a good sign.
Jameson is also a great name. You could always spell it Jamieson if you are worried about referencing the whiskey. Jamieson is a surname from Northern Ireland pronounced the same way. It also connects with Declan's Irish origin.
I think Declan goes so well with your daughter's name, Nora Cathleen. It's a good, strong Irish name and I feel that if you have loved it for ages, that is the first consideration. I don't feel it has the same likelihood of going the same way as Aidan (another great Irish name - it's such a pity it's been so mucked about).
While I can see why Jameson is a strong contender as a mn, I personally prefer James (a name I have always loved) as I think it flows better with Declan.
All the best!