I like [name]Maeve[/name] and [name]Saoirse[/name] off your list, and [name]Cormac[/name] on the boy’s side.
Girls
[name]Flora[/name] Very Scottish and very easy to say/read.
[name]Kathleen[/name] and [name]Caitlin[/name] Probably as straightforward and American-friendly as any of them get.
[name]Niamh[/name] Okay I just love [name]Niamh[/name]. And I’m American. Does that count? 
[name]Aisling[/name] and [name]Aislinn[/name], I love the former and my husband loves the latter.
[name]Aoife[/name] but she’s likely to get clumped in with all the little Evas and Avas.
[name]Branwen[/name] I just really like this. Might be Welsh though.
[name]Roisin[/name] is on our list.
[name]Siobhan[/name] My Irish-Australian husband is FURIOUS I won’t allow this one, but maybe you’ll like it. It’s certainly common enough in my (American) hometown.
[name]Elspeth[/name] [name]Love[/name] this one.
[name]Erin[/name] Does this count?
Boys
[name]Hamish[/name] Much, much more popular in Australia (and [name]Scotland[/name], for that matter) than in the US. But usable… I think.
[name]Gavin[/name] and [name]Gareth[/name]
[name]Lachlan[/name]
[name]Liam[/name]
[name]Malachy[/name] - Oh okay, my first love is [name]Malachi[/name], but this is nice too.
[name]Eoin[/name] and [name]Eoghan[/name] - The first is a favourite of my husband’s.
[name]Euan[/name] / [name]Ewan[/name]
[name]Corbin[/name] - I liked [name]Cormac[/name] too I just also like this one.
[name]Connor[/name] - Doesn’t get much more American friendly, though a bit popular for me.
[name]Fionn[/name] - I love this one.
[name]Oisin[/name] - Oh-sheen. Not as usable as [name]Owen[/name] in the US but about on par with [name]Eoin[/name], I imagine.