The equivalent could be gealgháireach: having a pleasant smile, sunny, radiant, cheerful, joyous.
meangadh i gcónaí always smiling
In Irish it's "buanghrá"
Éire go brách/Éirinn go brách in Irish Scottish Gaelic: ?
Caitlín go deo
Mo ghrá go deo
In Irish it's "go Lá an Luain"
As adjective, Éireannach go deo. If a noun, Na Éireannaigh go deo (the Irish people forever).
is linne go deo an bua
mo cheannsa go deo
"Gaelic" can mean "Irish Gaelic' or "Scottish Gaelic". They are classified as two distinct languages.
http://wiki.answers.com/Q/What_is_the_Irish_Gaelic_for_%27forever_sisters%27"
Níl an tsíoraíocht fada go leor