If necessary, cook the bacon according to one of my easy methods listed below. When cool enough to handle, cut into chunky, bite-sized pieces.
Meanwhile, bring a large pot of salted water to a boil. Add the pasta and cook until al dente, according to package instructions. Drain the pasta in a colander, then rinse under cold water to stop its cooking. Shake off as much water as possible, then place it in a large serving bowl.
In a small bowl or measuring cup, whisk together the ranch dressing: Greek yogurt, milk, olive oil, garlic powder, black pepper, onion powder, dillweed, salt, cayenne pepper, and Worcestershire. Pour over the noodles, then toss to coat.
Gently fold in the cherry tomatoes, romaine, spinach, 3 tablespoons chives, and reserved bacon. Sprinkle with additional chives for garnish. Taste and adjust seasoning as desired. Serve right away, at room temperature, or chilled.
TO STORE. This cold pasta salad will last for 3 to 4 days in the refrigerator. To keep pasta salad from drying out when you know you will have leftovers, make a little extra dressing (or reserve some at the beginning), then stir it in just before serving.
TO FREEZE. I do not recommend freezing pasta salad, as the noodles will become mushy and the dressing will lose its flavor when thawed.