I find conchigliette (aka small shell pasta) perfect for thin sauces/emulsions, soups and salads. This includes light meat sauces such as the slow cooked lamb shank and vegetable broth I show below.

Their ridges and shell shape grip and hold the sauce for that perfect mouthful. 

The next size up is called conchiglie and is great for heavier sauces.

Last but not least, the jumbo shells are called Conchiglioni and are perfect for stuffing with vegetables, cheese and meats. 

Dried conchigliette:

Here I have served the shells with a a light lamb shank broth, shaved Parmesan and sage: 

Enjoy,

PK

Here are some more pasta shape and pasta recipe posts.