They're all lovely names. I probably wouldn't go for Niamh for the reasons you mention. If you like a name I wouldn't let popularity alone put you off. I have a classic but unusual name and am only just coming round to it in my mid-thirties. I hated standing out at school and have often found people's preconceptions difficult to deal with. Always wished I was called Clare or Louise!
It's not a huge list, so why not wait until she's born and then see what 'fits' - you have 6 weeks before you need to register it and I think it's much easier to know if it's the right name once you're using it iykwim.
Niamh is a bit of an odd choice if you have no Irish connections. Wouldn't worry about the spelling though, she could learn it!
Freya v popular, as is Noah.
I love Harriet and Fraser. Annabelle isn't to my taste, and I've seen Elijah on here quite a bit which makes me think it's getting popular. Love Lucia, which way would you pronounce it? Loosha? Loo- cheeya? Loo-seeya?
I agree, I think all of the names on your shortlist are nice. Personally I prefer Harriet and Lucia from your girls list and Elijah from your boys, but I too would just wait until she(he) is born and see which suits baby best.
Thanks all. I'm just so indecisive I think if I don't have a firm idea of name this baby won't be registered for weeks Also, dd & ds are 10&7 and I wish now I'd chosen different names even though they obviously Suit their names now. I dont want to regret the name choice this time. I think I'm leaning towards Harriet (dhs favourite).