Mandatory:
feta
spinach
penne, fusilli, orzo, rigatoni
olive oil
Optional:
red peppers
artichokes
red wine vinegar
grilled chicken
salami chunks
carrots
sundried tomatoes
Rotelli, and lots of stuff. Pepperoncini, chunck of salami and/or pepperoni, provolone, artichoke hearts, pimento, eggplant, sundried and/or cherry tomatoes, cauliflower, carrots, olives, sometimes celery, pickled onions, capers, mushrooms, sweet pepper rings. Other things that are on hand or I see when I shop for the ingredients. Nobody ever complained about too many different things in the salad.
Oops; fail. I don’t normally use some of the ingredients you list as mandatory.
I’m a mayo and chopped celery kind of guy.
I’m sure I’d like the feta and spinach (I love both!) but it isn’t how I do it.
Tuna
Sweetcorn
Mayo
Job done.
Onion
Celery
Bell pepper
Garlic
Shrimp
Mayo
Dill
Salt
Shell pasta
Rotini with chopped olives and small cubes of pepperjack cheese, drizzled (not drowned) in Italian dressing.
I like almost any version, but the classic version Chez Athena is:
elbow macaroni
Italian dressing
bell peppers (red/orange/yellow)
red onions
tuna
cubes of cheddar cheese
peas
mayo
salt & pepper
fresh parsley if I have it
Ratio of pasta:veggies about 1:1. Toss the macaroni with the italian dressing while the macaroni is still hot. Use only enough mayo to get it to stick together.
Just made some last night.
Bow tie pasta
Cucumbers
Tomatoes
Black olives
Feta
Fresh basil
Marinated red bell pepper
Zoe’s Greek salad dressing
Or
Pasta
Tuna
Mayo
Black olives
S/p
Crunchy fried onions mixed on top.
Small shell pasta
Chopped onion
Chopped celery
Shredded carrot
Bacon bits
Ranch dressing
Salad shrimp
I feel like such a freak! 
I don’t know why but I love farfalle, but only in pasta salad context. I don’t think I’ve ever had it any other way.
I don’t care much about pasta shapes but more often than not I’ll just go for plain elbow macaroni because I always have it handy.
Olive oil is my usual base but I always add some mayo for body and cling. Sometimes I use the oil I drain off from my can of tuna.
Add onion, celery, green olive and carrot all finely diced. Some kind of cheese, usually parm or feta but it’s most all good.
Chopped sweet pickled peppadews are always welcome as is that pseudo-krab made from chopped fish and artificial flavors.
When I’m making it strictly for my own consumption then I’ll throw in a couple of whole boiled and peeled eggs and just cut them up as I eat the salad. I don’t like throwing cut eggs into a salad because the yolks tend to get kind of nasty to me. I don’t have this problem if they stay whole until it’s served.
Total fail, because I don’t use 3 of your “required” ingredients.
My basic pasta salad is:
tri-color rotini
diced salami
sliced olives
halved grape tomatoes
parmesan cheese
diced cheddar cheese
julienned red peppers
Gerard’s Greek salad dressing
I saw a pasta salad recipe called “P’s and Q’s”. Using alphabet macaroni (VERY hard to find), frozen peas, finely diced cheese, and Italian dressing. I used a small macaroni (either tiny shells or ditalini), boiled and threw in frozen peas just before draining. Shredded or finely chopped some gruyere. I guess you could use other cheese. It was simple, and delicious.
Hot and covered in marinara
My other favorite:
elbow macaroni
butter
salt
Comfort food from my yoot.
Cavatappi
diced celery
diced cucumber
diced red bell pepper
diced carrots
sliced black olives
sliced green onions
chopped fresh parsley
Newman’s Italian dressing
grated parmesan
This may not fit into the category of pasta salad, but . . .
Brown some freshly chopped garlic, add olive oil into the pan, then pour and toss with spaghetti. Not only is it really tasty, but the smell it creates is godly.
Penne or fusilli
Gorgonzola
Spinach
Mayonnaise
Grilled chicken
Walnuts
Grapes
Optional:
Green peppers
Red peppers
Add some finely diced serrano chiles or some red pepper flakes and you have spaghetti alio y olio.
tri-colored rotini
pack of frozen mixed veggies (usually a combination of green peas, carrots, lima beans, corn)
crab meat
parmesan cheese
italian dressing
cilantro
black pepper