It was only a few years ago that beach dwellers couldn't find so much as a blender in the Coronado area and had to make a trip to the city to make such a purchase. Nowadays, you can find pretty much whatever you want right here.
The Machetazo is a super-store with three floors and carries everything from groceries to art supplies, tools to linens, household appliances to sporting equipment. We have brought home such treasures as a kettlebell (last one, and on the top shelf...) and a pickaxe (we have some landscaping to do).
This is my second favorite spot for groceries. They tend to have good produce and a decent selection overall, and they have a little restaurant.
El Rey is the grocery store where I do most of my shopping. They also have good produce and a better selection of items I buy -- for example, non-dairy milks. Machetazo usually has, like, 18 varieties of soy milk (also not a milk I want to use) and sometimes almond milk. At El Rey I can find those plus coconut milk (my favorite), oat milk, hazelnut milk, and more. I love it.
We didn't like Super 99 the first (and for awhile, the last) time we went in. The produce was horrible, and there was a sort of sense that we -- as foreigners -- just weren't welcome there. I went in once with a friend when she had to pick something up, and I noticed a few items on the shelves that I hadn't seen at the other two stores -- a sighting that convinced me to give it another try. I now buy peanut butter and coconut milk there (cheaper than the other places and always in stock) and browse for other things -- but I still get my produce at one of the other places or a roadside stand.
Organica is a small organic and natural foods store, which I love. They only stock about once every two weeks, so sometimes the shelves get pretty sparse, but it's a great place to buy flax and chia, non-wheat flours and other gluten-free items, natural laundry detergent and cosmetics, and more. Note that most things here are pretty expensive, even moreso than what they would cost at a similar store in the states, but this is the only place to find certain things so if you want it badly enough, you just pay up.
Novey is a good place for garden hoses, lawn furniture, and, for us recently, a water filter. They have a pretty good selection of stuff, we just tend not to go here very often since they don't carry groceries and that's what most of our shopping needs are.
Now, in the city there's a magical place called Price Smart -- a membership warehouse, Panama's answer to CostCo. We have not been there yet, but we have a lot of friends who go regularly. It is, apparently, the best place to buy meat as well as to find imported goods that you won't find elsewhere. We have one friend who always brings us back a giant bag of pistachios, and another friend has brought home (not for us, unfortunately) a bag of dark chocolate acai blueberries and a large package of goat cheese.
Riba Smith, with a few locations in the city, is another large grocery store with a lot more imported items.
Overall, we find living in Panama to be much more comfortable than Argentina, as far as finding the foods we enjoy and want to cook. Produce more strictly follows the seasons and locality than it does back home, so we don't find many berries or cauliflower, for example. If it doesn't grow here now, it will be much harder to find -- which is kind of nice.
The only things I'm still requesting from home at this point are cinnamon (tastes like brown powder here), turmeric (despite the large selection of spices, imported and local, turmeric is not on the shelves that I've seen so far), protein powder (they have it here, but most of them are soy-based, others are quite expensive), and jelly beans (one day they had Jelly Belly at the Super 99...I have not seen them since).