depends what you're looking for- citywest is very small-apart from Dunnes Stores, only one ladies clothes shop and it may not be your cup of tea.
The Square in Tallaght is bigger but again depends what you're looking for in ladies fashions- it has debenhams, a-wear, heatons, places like that- Dundrum is way more upmarket in terms of the shops...but depends what you're after- if its just to pass the time then the square is probably ok for an afternoon...for serious shopping e.g to get an outfit-I would much prefer Dundrum...but it's more of a trek for you I guess....
Also Avoca have a large store near Saggart-just up from Citywest...there is a cafe there too...