It may be time to consider a single new lens that will handle more of your photography needs.
Granted, there are many wonderful lenses available for each different DSLR, and when you have time to think about and set up your shot, you should reach into your camera bag and get that special lens that will handle the shot to perfection.
Prime lenses are considered by many photographers to be the best quality you can buy.
And if your budget allows, you can fill up your bag with the best glass that money can buy.
But even then, you will want to have a great all purpose lens so you can take quick action when necessary.
Here are a few things to consider:

1. Image Quality - this is always the first consideration when choosing a lens.
   If all the other factors are tops, but the final photo is not clear and sharp, you may as well leave your wallet in your pocket.
   Image quality is king when it comes to choosing a camera, lens, or any peripheral camera equipment.
   
2. Glass - the quality and treatment of the glass used to manufacture the lens is of great importance.
   Manufacturing technology has advanced greatly over the past few years.
   Now there are special techniques and coatings that will eliminate distortion, lens flare, and other things that cause deterioration of digital images.
   
3. Build quality - some lenses are just built better than others...
   better materials and better glass.
   Cheaper lenses may use plastic parts that break more easily.
   
4. Focal Length - for an all purpose lens, you will want a greater focal range.
   18mm at the short end is optimal to get the landscapes and wide angle interior shots.
   And now that there are better manufacturing methods, you can get good lenses with 12x or greater zoom, so that the long end would be 200-270mm with still good image quality.
   
5. Image Stabilization - lenses with built in image stabilization (or optical stabilization) make it possible to hand hold your camera in low light and still great sharp shots.
   Without image stabilization, you will be much more dependent upon your tripod.
   
6. Cost - there is an extremely wide range of costs when selecting a walk around lens.
   The kit lenses will be your least expensive, however, kit lenses do not meet all the other criteria mentioned above.
   You should plan on spending $500 or more for a good quality all purpose walk around lens.
   You should also look into manufacturers other than your camera maker.
   Sigma, Tamron, and Tokina make some excellent lenses that fit on Canon, Nikon, Pentax, and Sony.