I makes all our sauces, out of all the ones you mention pesto is easiest and a favorite for Lent because the sauce requires no cooking, just fresh basil, olive oil, garlic and pine nuts in a chopper then it is so easy to boil up some shrimp and toss them into the pasta & dinner is done!
Marinara is easy, I like the San Merican Tomatoes, Whole Peeled. Oil and fresh garlic into a pot, either a onion sliced in 2 and fished out later or shredded with cheese grater, I add 5 cans of tomatoes and crush by hand or with immersion blender then cook bubbling on low on the stove at least an hour. The 5 cans make at least 4 meals for my family, one that day and 3 to freeze.
Bolognese is out for Lent, no meat but I am making it this weekend and while it works with pasta although we prefer fettuccini.
Rachel Ray Alfredo sauce is great with any pasta an also works with shrimp, I leave out the meat during Lent.
Rachel Ray's "Won't be single for long" Vodka Sauce is quick and easy and works on any pasta you like, shrimp easily adds protein.
I've been considering making Carbonara without the meat during Lent, I think the egg and cheese would be enough to pull it off.
For Lent I do a decent amount of cheese tortellini because it is heavier and more filling. Works with pesto and Alfredo and even in broth (which is allowed), it also works great in a salad with celery, tomato and other random veggies with some Italian dressing. Ravioli is another heavier pasta option during Lent, it is amazing filled with cheese or mushroom. Manicotti and stuffed shells also extra filling. Lasagne and baked ziti are the kings of heavy but meatless pasta dishes for Lent. Basically add ricotta and things go from yum to everyone is stuffed fast
