well beep there are a few. things to consider is your canon has a 1.6 crop factor. that means that, your lenses act like a lens that is 1.6 times its field of view. so a 50mm acts like a 80mm.
on the huge super zooms there is a lot of compromise. but since you are looking to practice and use it for snaps at disney, i dont think you will be bothered much by it.
canon, sigma, and tamron make a 28-200 and a 28-300. so its like a 45-320 and a 45-480. these are slow on the long end thus bluring usually happens. sigma and tamron make a 18-200 these are like a 29-320 on your camera. the sigma is $379 and the tamron is $389. sigma also makes a 18-125 which is a 29-200 and its cost is $279.
which one is right for you? check out the testing at slrgear.com.
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