When choosing a sofa, think of it as a commitment. Here are some tips before you buy.
The average person buys a sofa every 10 years, so don't go too trendy. It's much easier to change out pillows with the new trends then to buy a new sofa.
Durability/Comfort - Invest in a hardwood frame (poplar/maple). It's sturdy and durable. A sofa with a well-made frame and springs can last 30 years. MDF or soft woods, while less expensive, can breakdown and crack.
This sofa is from Crate and Barrel. Its well made, classic, comes in a variety of colors and a great investment. http://www.crateandbarrel.com/furniture/sofas/petrie-apartment-sofa/s668268
Cushions - High density foam is the least expensive. A full spring core with a poly or feather and down casing will cost more but last longer. 100% Down is the most expensive choice but it requires fluffing and more maintenance.
Get a classic shape - Reupholstering generally costs less than half the price of a new sofa and will create a whole new look.
Before you buy - Ask yourself will I love this sofa in 5 years, 10 years...And make sure you measure not on the space where your sofa will live, but measure your doorway and stairs.
CHAIRS
Urban Home is my favorite place to buy Occasional Chairs for my clients (and myself!)
These 2 chairs are a steal for under $200 each.