Have friends with kids at Westland but live in SS. Have also heard good things about new principal at Sligo. You might also consider SSI, which people are happy with.
Westland atmosphere appears to be ritzier focus, more catty and mature for girls, from what I've heard, than some of the SS schools. If your daughter isn't really into fitting in with the crowd at a level that may be hard on your income, you may want to factor that into your choice.