Most of these were shot with the 18-200mm VR ED lens, but some of them with the 75-300mm lens. The latter has less vignetting as it is designed for full-frame cameras. The very best panoramas are made with a simple prime lens whose barrel distortion characteristics are uniform and thus easily compensated.
Panoramas can be constructed easily with Adobe Photoshop (Elements 5 and 6), not so easily with Hugin although I think Hugin can take larger inputs and multi-row panoramas. A multi-row panorama is an amazing way to turn your 10 megapixel camera into an 80 megapixel camera. Panoramas can be vertical, as for instance shooting a tall building. During the processing, you can specify nice features such as vignette removing and whether to display it is a panorama (buildings have curved edges) or rectilinear (buildings have straight edges). Beware choosing rectilinear if your angle of view is more than 45 degrees; edges may be straight but you'll have some strange size and shape distortions on the left and right of the result, same as you get from an extremely wide angle rectilinear lens.
I don't put the full size images here, they're WAY too big. The HUGE size is actually 1/2 the size of the original stitched panoramas and as you can see they are very sharp. In fact, using panoramas at half size gives you the same pixel count but is much sharper than just using all 10 megapixels out of the camera.
Be sure to allow plenty of overlap for computer assisted stitching. In olden days of manual stitching you went with as little overlap as possible but the computer needs about 1/3 frame overlap to discover matching points and also calculate barrel or pincushion distortion and compensate for it. What that means is that if you want to double your resolution (for instance a 4-shot two-row panorama with the same aspect ratio as a normal photo), insert some "in between" columns and rows to guide the software. That means shooting 3 rows of 3 to end up doubling the resolution of your camera.
Forget large areas of sky in automated panoramas. The computer won't be able to match frames. In this situation Adobe Photoshop (or similar) would probably be better since you can just place the sky photos where you want.
Beware moving things. Don't let clouds, cars, or people be matching control points. Hugin seems to be better for this as it allows you to review and edit the control points. If your horizon is wavy, you can probably blame it on a control point moving.
Hugin has an option to keep the intermediate TIFF files. These are rather large and most of the time you will not want them; but if someone is walking between the two shots you can have some strange result where half a person or half a car is visible. What you do is load up the appropriate intermediate file and "clone" the car or person into the result so that you have a complete car, person or whatever else moved between the shots. In one of my more interesting construction photo panoramas, the same worker appears three times in one panorama!
Your computer will need a LOT of memory. If you have only 1 gigabyte, plan on a few hours putting together a 15 shot multi-row panorama.