spicy — You really should just mix hot sauce into commercial salad dressing yourself (bonus: this allows you to choose your own spiciness level). There's a problem that occurs with creamy (or oily?) salad dressings, as well as with people who use a large amount of salad dressing — these salad dressings end up nullifying the heat level. (see the Mythbusters episode that found that dairy products are best for cooling the heat that's already inside your mouth) It makes sense to scale up the heat along with the amount and type of salad dressing, so it really should just be mixed in with the salad dressing to begin with, instead of including, for example, diced jalapenos in the salad mix.
thermal variety — warm chopped meat, cold salads,
other variety — onions, avocado, feta cheese, apples,
augmenting our home salad kits — baby tomatoes, real bacon bits, croutons, shredded carrot, onions, black olives
roasted veggies — broccoli, potatoes, carrots, bell peppers, Brussels sprouts