I know where three Smiles are located. I found some decent packaged ham at Smile that was better than what I could get at Lucky. Actually the best bread I could find was the hotdog buns at Smile.
I don't think the need for certain flavours from home ever fades. As much as I enjoy foreign food I still yearn for farang food often. I love bread and Thai bread is appalling. However, in Cambodia bread is readily available anywhere in the form of gorgeous baguettes and I consume a fair few of those, plus the sliced bread is more or less the same as back home and it's lovely toasted.
I recall one of the other Smile stores being further up Street 136 (away from the River) on the corner of Street 19, but the location of the third Smile escapes me. But there are several other similar stores operating in much the same way too, plus Lucky Supermarket at the Sorya Center near the Central Market.
I thought the sliced bread was dreadful, thick and dry. The sliced wheat bread you can get at 7-11, and almost everywhere in Thailand, is excellent IMO. But different strokes I guess. I don't usually eat white bread at home just whole wheat. I'm not really a baguette lover. But in a former French colony that is the most logical. Barang groceries in general might affect my decision to spend as much time in PP as you. Otherwise Cambodia is about the only place left in SE Asia I might actually consider moving to some day.
The third Smile (I think) is on street 51 a few blocks from Roundabout? Just past the school. I think that is a Smile but I might be wrong. It has been a while. Whatever it is it was about the only real convenience store around in 2008. There are a couple more Smile listed in the Yellow Pages and neither are the two we know on 136.