As detailed in the other post, I bought in Raphoe Road in Crumlin a few months back and have moved in recently after finishing the first phase of renovations.
We are at the cul de sac end and it really is very very quiet and we love it so far. I definitely recommend the privately built parts of Crumlin as the houses have real character and those areas are very quiet, and of course the bus service and easy access to shops etc is great.
I'd buy another house on Raphoe Road and do it up as soon as I get the cash, but Iveagh Gardens, Old County Road and places like that are high on my list aswell.
As mentioned, personally I wouldnt buy in Captains Road or anywhere around the bangor circle as these areas are quite wild IMO based on experience and my girlfriend avoids these areas when walking home from work. You'd be surprised at just how localized anti-social problems can be: 5 minutes walk from my house are some quite dodgy areas, but where we are has been perfectly quiet and incident free since we bought 6 months ago, touch wood.
Good luck with it, and get in soon if at all cos the prices are going up quikcer than most other areas - just look at what happened in Drimnagh for an example of how high prices could go.