nintendo zone is what supports the streetpass relay point. So places that have the one should still have the other, the employees (unless they're gamers) tend to not know about it at all.
I get a lot of funny looks strolling through the home depot next to my work, looking at the flowers, not buying any and walking back out just to get streetpass hits, but I am rarely disappointed. I just haven't gotten up the nerve to go in and open up to try to download the dlc... Conveniently I also have a bestbuy in my work shopping center, though their wifi isn't as quick to hit my systems as home depot's is.
I have always had issues with mcdonalds, I can pick up streetpasses from them if I'm actually inside the building, but have never been able to get a download from them. My preferred one is sitting down at a bench or table inside barnes and noble. Though I haven't in a while, maybe that's where I'll try for my mask.