Couch: if you treat it well it could last you forever. A good couch is built to be durable. Buy something you love because it'll probably get more use than any other piece in your house. That being said, try to pick something with a relatively neutral colour. There are some beautiful patterned couches out there but chances are your tastes are going to change along the way. If you're desperate for some funky/trendy patterns in your living room try some decorative pillows and throws.
Chest of Drawers: something like this can be used in almost any room of your house. So whether you never move again or you move 100 more times, you'll always find a great place for it. Not to mention it's relatively easy to paint the piece another colour and change the hardware. That way it can change along with your tastes.
Original Art: don't be intimidated by the prices of the art you see hanging on gallery walls. You can find plenty of great stuff in local art schools or sites like Etsy. They're good investments and are easy to store if you want to switch up the look of a room. An original piece of art can make any room look like a million bucks.
Anything Antique: antiques are always a good investment. If the piece is till in good condition after all these years, you know it's durable. They have a lot of character and add personality to any room. If nothing else, they can become a room's statement piece and a real conversation starter.
Bed: they recommend 8 hours of sleep a night so thats 33% of your day. That deserves a decent investment. If you buy a good mattress it can last you a whole decade. A good sleep sets the tone for your whole day. So essentially a good mattress can change your whole life...right?
No one ever said banks were needed for a savvy investment ;)