Cook the bacon: In a skillet over medium heat, cook bacon until crisp.
Transfer to a paper towel-lined plate, then crumble when cool. Reserve a teaspoon of bacon drippings if you like for extra flavor in the dressing.
Prep the chicken: If using rotisserie chicken, remove skin and bones, then shred or chop. If using leftover or freshly cooked chicken, dice or shred into bite-size pieces.
Make the dressing: In a large bowl, whisk together mayonnaise, Greek yogurt, Dijon, lemon juice, garlic, smoked paprika, black pepper, and salt.
Add olive oil and reserved bacon drippings (if using) and whisk until smooth and creamy. Adjust seasoning to taste.
Toss the chicken: Add the chicken to the dressing and stir to coat evenly. Let it sit for 5 minutes so the flavors soak in.
Add the mix-ins: Gently fold in tomatoes, bacon, red onion, and herbs.
If serving right away, fold in the chopped lettuce and avocado. If not, wait to add lettuce and avocado until just before serving so they stay crisp and vibrant.
Serve your way: Spoon onto toast, stuff into lettuce cups or a wrap, or heap over a bowl of greens. Finish with a crack of black pepper and a squeeze of lemon if you like.