broodymum - i love gaelic names too. i have to spell out my name constantly and its a normal name. i get does it end in i, y or ie and then does it have an e on the end so normal names aren't easily spelled either.
love hallie but would use it as a pet name for harriet. is arwen pronounced are - win?
i like caelan and cailin which is similar to Cailean. cailean can be pronounced in the same way as either and also gilean and kilean.
i like dara for both and also DÁIRE for a boy which is pronounced like dora.
i prefer the spelling xander to zander.
niall is lovely and other gaelic names i like are derril, dorrin, carr, derrie, herbie and derbie for a boy and kari, kearie, kay, terrin, derrin, derron, darrel and kerrie for both.