Question: What are the best type of woods to use for building finished interior stairs, i.e. pine, maple, oak, etc. Curtis
Answer: Curtis, the best type of woods for building interior stairs in the final finish stages (i.e., handrails, newel posts, balusters, etc.,) are any of the hardwood species such as oak, maple, poplar, beech, cherry, etc. The most common is red oak which has several plus's: it is easy to work with; it can be stained to match anything in the house; it is durable and long-lasting. Maple, whether soft or hard maple, is another good choice, though maple has restraints in color and staining. Poplar is the best choice for painting as it is inexpensive and tight-grained for smooth finish. Clear poplar can be stained to match Brazilian Cherry. Many of the other hardwoods, such as walnut, mahogany and Brazilian cherry are best clear coated to enhance their natural colors.
Woods like hemlock and firs are "okay" for stairs, but do not last long, are prone to a lot of customer service work. This is usually due to the fact that these are soft woods and don't have the longevity of hardwoods.
For hardwood and softwood samples click me for color illustrations (all done in clear coat).