Yeah we bought our house because of the garage (there was a similar one but had no room for a double so it put us off it and made us pay a little extra for our one IYKWIM).
Dal, Rolleston was never my first choice either but after having lived in Burnham for a year and then Rolleston for a year before moving back into town (plus Mum and Dad have lived out there for about 6 years now) I would have to say it's pretty good. The only problem you really find though, is that it takes a lot longer (generally) to get from Rolleston to town than it does from say, Kaiapoi to town, even though they're roughly the same distance, simply because Main South Road is shocking in peak traffic and is only one lane.
But... if you had to travel across town to see your family a lot if would be a PITA I reckon. All my family lives out the south side of town (Rolleston, Burnham, Dunsandel and beyond) so it would appeal to me but it would be a long way to travel if you wanted to go to your parents for tea when you've got the kids etc (free food after all

)
I say enjoy your smaller mortgage and bits of savings, and get those wooden blinds love