What sheen should I paint my interior is a great question to ask before you begin a paint project on your home. There are many options for you, depending on your preference and budget. The main thing we should think about is what end result you want. What purpose is the paint serving you? Is it for protection or decorative? Is there moisture in the room? Do you expect heavy traffic?
Common Paint Sheens Used on Interiors; From Gloss to Flat
Gloss & Semigloss
Gloss and semigloss paint sheens are commonly used for trim and doors as well as bathroom and kitchen walls. Glossier paints can withstand more touch and washes than the less glossy paints. Glossy finishes will not touch up well and require more prep before painting can be done. Generally you do not want to use higher gloss paints on main walls, as the reflective nature can cause a room to feel uncomfortable. Glosses and semi glosses have high to very high durability. 
Satin
Satin paint sheens are great for high traffic areas that will need washed frequently. Expect a velvety finish when painting satin. This looks great on walls in common areas. The flaw to the satin sheen is that it can show brush strokes and roller marks easily. Therefore, it takes higher skillset to apply properly, and touching up is not suggested. With the higher gloss, satin sheen has high durability. Book An Estimate
Eggshell
Eggshell paint sheens are great for low traffic areas that will not need touched up or washings. Expect a smooth finish that looks great for more decorative situations. Perhaps a family room with your expensive furniture. With little gloss, eggshell has medium durability.
Flat or Matte
Flat or Matte paint sheens are most commonly used for bedrooms and the lowest traffic areas in your space. This is great because flat paint is less expensive. But it can also be a problem because flat paints generally do not withstand any washings or heavy traffic. Flat paints generally have low durability and zero washability, unless working with mineral paints. Mineral paints are less commonly known by general paint contractors, but are well worth the search. Book An Estimate
Tips For Choosing Paint Sheen
Dark Colors
If you are choosing darker colors for your walls, you will want a lesser sheen. Darker colors require more pigments, which add to the sheen. Therefore when choosing dark colors you will want to drop your sheen down one notch.
What Purpose is the Paint Serving?
The main reasons we paint surfaces are for decorative purposes or for protective purposes. This is an important question to ask before starting your painting project. The answer will be a factor in the sheen you can expect to use. For example, a room with very little traffic and expensive furniture will want a more decorative finish. Whereas a hallway or bathroom would serve more as a protective finish. The beauty of paint is that certain products double as both protective and decorative, without any sacrifice in quality. That said, they can come at a higher price.
Moisture, Bathrooms and Paint Sheen
Bathrooms are generally painted for protective purposes. Therefore we need to think about sheen being protective against moisture and issues like mold and humidity. In order for paint to repel moisture and combat mold, it generally needs to be a higher sheen. That is why you will see most bathrooms painted with an eggshell sheen, or even some higher moisture/higher traffic bathrooms being painted with a semigloss finish. This allows for the walls to be protected against moisture penetrating the surfaces and creating buildup that can lead to mold. 
High Traffic Areas and Paint Sheen
The glossier finishes are also more washable than standard flat finishes. The standard flat finishes generally come right off when you try to wash them. If you do desire a flat finish on your walls, you can use less common paints like Romabio. Romabio is made from minerals. Instead of drying to plastic like acrylic paint, it dries to rock. Romabio is naturally mold resistant and highly washable! Romabio is a great solution to having a flat finish that you can use in high traffic areas or even bathrooms and kitchens. Benjamin Moore also offers a line of paint for high traffic areas, called Scuff-X. Scuff-X is great heavy duty paint for hallways where lots of kids run and play and throw their shoes and toys. Protecting your walls with paint can save a lot of money in repairs throughout the years.