Good all around zoom lens for Canon DSLRs

I'm just a novice who is part of the huge wave of consumers buying DSLRs on the market now. I bought the Canon Rebel XT series, one of the most popular models.

Anyone who buys a DSLR does it to get the flexibility of using different lenses. So the question arises, which ones should I buy? There are lenses that range from very cheap to thousands of dollars. The upper end includes the famous "L" pro lenses by Canon which can easily range from $1-$2 thousand for the entry level models.

One of the much discussed choices for a medium zoom is this lens vs. the 70-200mm L lens. They are both around $500-650. This lens is obviously longer going to 300mm and with a 1.6 crop factor camera like the Rebel, it's even longer. It also has image stabilization which the L lens doesnt have in that price range.

This lens got a rave review by Ken Rockwell.
http://www.kenrockwell.com/canon/lenses/70-300mm-is.htm

Some people don't like Rockwell due to his forceful views but I find his site informative. His point is that in real life vs. the artificial tests in labs, it's about as sharp as most people need and that the added fact that it's relatively small, light, unobtrusive and relatively inexpensive for doing so much in one expensive, make it a top choice. The lens isnt particularly fast but also has image stabilization and decent autofocusing. In the consumer grade lens field Canon does have cheaper zooms but they tend to be worse or have less features than this one.

It's gotten very good reviews at other sites:

You can see the difference in size and weight in this review.
http://www.the-digital-picture.com/reviews/Canon-EF-70-300mm-f-4-5.6-IS-USM-Lens-Review.aspx

http://www.bobatkins.com/photography/reviews/ef_70_300is_review.html

A lot of picky people mention that this lens can be soft in the long end. Many snobs say it's not an L lens. It is however, lighter and smaller, making it easier to carry around as I mentioned. It's also black making it less garish.

Having a large, heavy, white lens may seem a bit too much for many people.

The L lenses are white and black which some people like and others find annoying. I think it makes the lens stand out too much, but many people like the fact knowledgeable people can immediately tell you have a L lens, sort of a snob factor. Ive read that the white reflects light/heat more which can affect the lens. I have no idea if that's true.

The 70-200mm L lenses is fawned over for the sharpness it have all through their range but the version of the 70-200 4L that's less than $1000 doesn't have IS, image stabilization. Supposedly indoors, situations where there isn't a lot of light IS can help to reduce blur. IS also helps when you are using the long end of the zoom since hand movement is magnified.

How important is IS? Some people think it's very important while others dont.
http://www.kenrockwell.com/tech/image-stabilization.htm

The 70-200mm L doesn't have it so some people say it's far less sharper in everyday usage in various situations where there is low light. People who dont mind it say they use a tripod or shoot mainly with decent light or have very steady hands. The L lenses are also known for their build quality and fast,silent focusing.

I kept going back and forth on this one. The 70-300mm with IS is currently around $540-600 while the 70-200mm L no/IS is around $560-650. A huge discount randomly popped up at the time I wanted to buy it, so I decided to go with the 70-300mm. I'll probably get the 70-200 L 2.8 non-IS which is currently $1000-1200, in the future as I want a faster lens for capturing motion.

One comment, some of the reviews mention that there was a fix for the 70-300mm a year or so ago. People noticed it wasn't that sharp in portrait mode which Canon fixed for free. Also some people mention when the the lens was extended it felt floppy, that was also supposedly fixed.
Another factor is the 70-300mm rotates when the zoom is extended which causes a problem if you use a polarizer filter. The L is a fixed length lens.