I actually never get sick of salad. But, yes, the secret is combining: cheeses, nuts/seeds/croutons, and the freshest seasonal ingredients.
Epicurious helps for the occasional inspiration.

Another idea is to add roasted vegetables, for example roasted sweet potatoes over arugula with halloumi cheese, with a lime honey dressing.

I never much bother making dressing, a splash of citrus or vinegar and a drizzle of oil will suffice and safe time.

Raisins, nuts and raspberry vinaigrette.

Mmm, sweet potatoes over arugula with halloumi cheese and a lime honey dressing sounds delicious.

I like combining chickpeas with beets, feta or goat cheese, cucumber, parsley (if on hand), and red onion with a red wine vinaigrette. It's filling, vegetarian, and healthy. You could also add grape or cherry tomatoes, too, if you like them.

I'm also a big fan of olives, pickled jalapeno slices, and hot banana peppers. I'm always up for an Americanized Greek salad. For a Mexi twist (and a treat) -- crispy corn tortilla strips.

I used to work in a restaurant where we made a dressing out of salsa and ranch. It was full of flavor, and the salsa addition helps to bring down the calorie count of the ranch dressing naturally.

I oftentimes will microwave a sweet potato for 2 minutes and it's a delicious add in.

A few more of my fave add ins?

-walnuts
-goat cheese
-sugar snap peas
-cherry tomatoes
-sprouts
-butter beans

Two of the most important, and often underused ingredients in a good salad, are salt and pepper! It'll bring it all together. This is coming from someone who eats a salad the size of my head on the daily :-)

I rarely make salad dressings (occasionally I'll make a classic French mustard-based dressing or one yogurt-based one, but increasingly rarely). I have gotten fabulous oils and vinegars though; special ones make your salad. Right now, I have some fabulous French olive oils, as well as lemon and mandarin olive oil. And balsamic vinegar from a visit to Modena this spring. (I might splash some lemon or orange juice instead of vinegar).

Lately, I've been adding various seeds. Here in Switzerland they come mixed at the grocery store, so I am not sure of all that is in there. I do recognize the pumpkin and sesame seeds though.

Also important is to vary the way you cut your veggies -- it changes the taste and whole experience of the salad.

how about just non-lettuce salad? like red or green cabbage? shredded carrots? steamed broccoli?

broccoli with sunflower seeds, chick peas and feta is a favorite of mine.

I like the non-lettuce option. What about quinoa, bulgur, or cous cous with tons of veggies? Throw in whatever nuts or beans work with it.

Warm brown rice, green onions, sliced cherry tomato tossed with a oil and vinegar dressing. You can add parsley and other things to brighten things up.

my favorite addition is dried cranberries & sunflower seeds

There are some great ideas above. When I make a salad that is going to be a meal, I always include a protein item:

-hard boiled or poached eggs
-leftover roast chicken or beef
-pan-fried or steamed fish
-halloumi
-chopped ham

My husband and love a big salad for a weeknight meal and we make double to take to work the next day for lunch. They are so pretty and nutritious.

My usual add-ins that aren't listed yet include cooked pasta, lentils (green or black ones that keep their shape), and chopped herbs. One of our fall favorites is spinach & arugula, roasted zucchini, cherry tomatoes, chevre, and toasted walnuts tossed with a handful of hot pasta and some flavorful olive oil/balsamic.

Two more salad ideas: in Italy, we had a couple of salads with pearl barley (just a green salad on top, with grated carrot maybe... pretty free-form).

And lately, a salad I have made quite often (it's nice with hoisin grilled chicken, or pork chops for an easy dinner), is to finely shred a small Chinese cabbage, add grated carrot, and toss with salt, pepper and seasoned rice vinegar (or add some sugar to plain rice vinegar). Simple, but very, very good.

Also, I like topping salads with poached eggs. (especially like making Salade Lyonnaise)

Any and all vegetable and protein combinations. I figure this time of year, the more vegetables the better and combined with a little bit of protein via canned tuna/salmon, leftover flank steak or chicken, or canned beans combined with a little bit of fat from an avocado or olive oil is a good choice in the indulgent months ahead.

Everything listed in the post plus:

chickpeas, beans, and bacon bits made from real bacon.

Also, a light vinaigrette (olive oil red wine vinegar, fruit puree rice vinegar oil, etc)

Goat cheese, bleu cheese, corn, tortilla chips (not all on the same salad!)

My salad equation is:

lettuce
fruit (apple, pear, figs, red grapes, dried cherries)
nut (candied pecans, toasted pinenuts, raw almonds)
cheese (chevre, blue, brie)
quick vinaigrette

Usually once I've picked one ingredient, say a fresh pear as the fruit, the others are obvious (blue cheese and roasted walnuts).

I must say that here in France we don't eat complicated salads. I think they take away from the main meal and detract from the way they cleanse the palate after the meal. I will never get sick of good, fresh lettuce, vinagrette mixed freshly in the bottom of the salad bowl and think slices of shallots.

tapatio (or any hot sauce) plus ranch is good any time. add some beans and you're good. also a chopped italian salad cures me of my "ick salad again feeling" - with salami, peppers, olives, pickled peppers, cheese, splash of lemon. yum.

Balsamic drizzle, goat cheese, toasted nuts, fresh homemade croutons,

yum....

chickpeas, bulghur, aromatic herbs, feta, pomegranate seeds.

Spices-cumin and coriander are particularly adaptable, I also do a shredded cabbage salad with olive oil, lemon juice and caraway seeds.

Dressing: I particularly like a root salad I do with a cheeky bit of maple syrup (along with olive oil, lemon juice and dill) and some toasted pecans.

Pitta bread/toasted ciabatta to soak up the lovely dressing.

http://optimistafterlunch.blogspot.com/

I have a "method" that my friends have named after me. I use the colors of the rainbow:
Red = tomatoes (grape or pearl)
Orange = carrots
Yellow = yellow pepper
Green = avocado
Blue = dates (I know, not blue)

Then I top with pine nuts or walnuts and use goat cheese or fresh mozz. I only dress salads with olive oil and a sprinkle of fresh black pepper and sea salt.

Cilantro passion fruit vinaigrette made in my blender:
1 bunch cilantro (wash and throw in stems and all), seasoned rice wine vinegar, passion fruit pulp (Goya brand - I break off a few frozen hunks), olive oil, salt and pepper.

It's amazingly easy and flavorful, great on a spinach salad with chicken breast or salmon.