Trademarks only protect businesses in the same category as you from using the same name or slogan. That means there is no legal protections prohibiting an author from using the name of a real company or product in their novel. In normal situations, you are only required to use trademarks appropriately.
The big deal to most companies is that you spell and capitalize their name properly (e-Bay), that you don’t use it in a way that implies an endorsement, and that you don’t use it in a way that makes them look bad. You show a name is trademarked generally by capitalizing it (e.g. “Kelly tugged on her Reeboks.”
You can use real locales, however if you’re using a real place, you need to research to make sure you have things located where they actually are in the city, whereas for a fictional location you can make things up, which is not necessarily easier as mapping out a fictional city to make it feel authentic can be a lot of work, also. So, in most cases, using a real city versus a fictional one is entirely author preference.
However, there is one consideration when using real places and brand names in your work: slander and libel suits. Any setting or item used in a negative context is best left generic. For instance, if your plot requires health code violations in a restaurant, don’t name the restaurant Burger King. Likewise, if your character is locked in a battle with their local government or the story otherwise reflects negatively on the locale, you’ll want to use a fictional city.
Otherwise, it comes down to POV and characterization. What products would your character use? What terms would they use for them? What places would they visit or frequent? Whether your character takes a Kleenex out of her purse at the Olive Garden or a tissue at the Pasta King, whether your character buys Kirkland’s Signature toaster pastries at Cost-co or Kellogg’s Pop-tarts from Kroger’s says quite a bit about them. So don’t make those decisions lightly. If it arises in your plot, think through the situation carefully and decide what is best for your character and whether the usage would cast a negative light on the product or place, as again, that could potentially lead to a lawsuit. Otherwise, it’ll be up to your editor at your publishing house.