Meirish, I made a potato soup last weekend, loosely based on what you posted, but as you know, soup is its own journey, and takes on whatever we find in the fridge. I did the potato base, with garlic, onions and bacon, in homemade chicken broth, then when it was almost ready to serve, added sour cream, grated cheese, more bacon and some chives...loaded baked potato soup!
I use a lot of onion, garlic, scallion, chives, smoked paprika and thyme, I'd have to say those are my favourites, but I also keep Bay, sage, dill, oregano, turmeric, dried chilis, cumin and cayenne on hand, and they don't get stale! I use sweet spices, too, like cinnamon, nutmeg and clove, sometimes even in meat dishes!
I'm sort of split about the slow cooker vs Dutch oven, I guess in the long run it comes down to volume, if I'm making a bigger batch of something, its on the stovetop, smaller is slow cooker. Right now theres a ham bone simmering on the stove, because it wouldn't fit in the slow cooker!