I have the Happiest Homes Initiative and only have one house up there displayed. Can I visit another town and look through their Showcase to fulfill the 3 visits?
It has to be a new house (with yellow highlight). So it can be the same house, if you say visit the house once, then street pass the same person later in the day, visit it again when it's highlighted yellow, and then do the same a third time. This works if you own 2 DS's that have ACNL on it and just let them street pass each other the whole day.. But you can't just go in and out of the same house if it hasn't been newly street passed.