I love Maia. Though I much prefer Maya. Maija is pretty, but Maia is slightly more appealing. I love Elizabeth as well, it's currently on my list. Maia Elizabeth is gorgeous! Jānis is very cute and unique! A couple suggestions...
Opinions on Audrey Natalia Quinn/Natalia Audrey Quinn & Kellin James?
From your suggestions, I like:
Audrey Natalia is gorgeous. I prefer Quinn for a boy. I love Natalia Audrey too, though I think Audrey Natalia flows smoother than Natalia Audrey. The A's run into each other in the latter. Kellin is okay, but Kellan or Kellen look better. Kellan/Kellen James flows very nicely.
I love Maija Elizabeth! Maija isn't on my list, but I still think it's cute. This is the first time I've seen it, but I perfer the Maija spelling, too. Elizabeth has ALWAYS been on my list! It's paired with just about everything! I love it. As far as Janis (I'm not sure how to do accent marks) goes, I've never heard it that way, but I think it's lovely that you're honoring family. What style middle name are you going for?
Delia Jolie Claire
Mason Elijah Everett
Jānis is common in Latvia, though I was born and raised in the US. J in Latvian is pronounced like a Y. I don't know how to type the accents either except "é". I copy/paste them from somewhere when I wanna use them. For middle names, I like classic names (unusual names are fine, but no made up/ridiculous ones). Elizabeth is gorgeous. I'd use it as a first name if it weren't for its popularity.
I love just Delia Claire. Delia is beautiful! I really love that name too, but I don't know if it fits right with my last name. Jolie just reminds me of Angelina Jolie. I also love Elijah Everett, but Mason is way too trendy and popular for my liking.
Opinions on Noelle and Conrad? I'm not sure on middle names. I'm not completely sold on Conrad, but I don't think it's that bad. Christmas is my favorite holiday, and Noelle is the feminine form of Noël which is the French word for Christmas so I've always loved it. Christmas itself doesn't feel like a real name though, unless you're a Bond girl. lol