It may seem like an odd place to start, but it's often the first thing people see in your home, so if you want to make a good first impression, this is where to start!
Having said that, decorating the hall, stairs and landing can be one of the most expensive decorating jobs, not because of the surface area of the walls, but because of the amount of woodwork involved - rubbing down and applying two coats of paint to all the doors and door frames can be the most time consuming part of painting a house, and if you add spindles, bannisters, and so on into the mix, it's a big investment. Not as much as a new kitchen or bathroom of course, but certainly one of the more expensive rooms when it comes to purely decorating.
Despite the fact that most of the photos here show wallpaper, I often don't recommend hanging wallpaper in "high traffic" areas, because of the risk of danage to the paper as people brush against it. If you have a lot of people coming in and out, children or dogs (or any other regular guests who are likely to make a bit of a mess of your walls), I would usually recommend a hard-wearing paint which will withstand regular cleaning, such as a durable acrylic matt or eggshell.
In many cases I'm not a big fan of using wallpaper in hallways and up the stairs - these are "high traffic" areas, and if you have a lot of people coming in and out of your house (kids rushing in with school bags, for example...) there's always a risk that the paper will get damaged. However, as you can see in this instance it works really well to create a very calm, sophisticated feel.
In this instance we wallpapered one wall only, as a "feature wall" which creeted a fun, "funky" feel. This was further enhanced on the opposite wall (see third photo), where we created a picture frame out of dado rail, painted silver and fixed to the wall. Inside this frame we hung wallpaper of a different design to the feature wall, but using the same colours. The client then hung a piece of 3D artwork inside the frame.
Sometimes, especially when light and/or space is limited, keeping things simple is a good idea. With that in mind, we painted all the walls a soft cream colour in this hallway, and kept the natural wood a light colour, rather than staining it dark before varnishing. The beauty of natural wood - apart from being able to see the natural wood grain and so on - is that it acts as a "neutral", so almost any colour scheme will work with it.
Once the decorating was completed, to make good use of the space under the stairs I built a storage unit from some plywood, stained and varnished to match the stairs!