Before I start, understand that I am not a fan of zoom lenses - modern fast, constant aperture models excluded. While these more modern lenses offer exceptional image quality, they are big, very expensive, and won't fit your camera anyway. Consumer quality zoom lenses compatible with your camera are big, heavy, slow, and offer only mediocre image quality. Good enough if you want only 4x6 prints. A disaster if you're looking to make some quality work. Forget them. There's a reason they sell so cheaply on the used market.
Originally Posted by Caipré
You already have a 50 mm lens, so you're covered there. The Canon 50 mm f/1.8 lenses are all good. Stepping up to an f/1.4 optic gives you only 2/3 stop more speed that you'll rarely (and I do mean rarely) ever need. With only very few exceptions, none that fall within your criteria, all the 50 mm lenses I've seen do not perform exceptionally well when used wide open. For the best image quality, any of them need to be stopped down to at least f/2.8.
I find the 135 mm. focal length to be a bit too long for the way I work. I'm assuming you're talking about the Canon branded lens here, and if so it is a really nice lens and pretty fast one for its time. Keep it. Personally, I prefer something in the 85 to 105 mm focal length. Since you already have the 135, I'd lean closer to getting something around 85 mm with a fast aperture of around f/2. With that lens, you'll be able to work close in enough to make really nice head and shoulders type portraits while maintaining a natural perspective. A 135 flattens things out too much and the 50 adds to much prominence to noses.
At the wide end, I'm not that crazy about the 35 mm focal length. It will give you a wider angle of view than the 50 mm lens, but it's not different enough from the 50 mm lens to make it truly different. The 28 mm focal length is good, but even that looks almost normal to me. In wide angle lenses, I've found the 24 mm focal length to be the most useful. It's wide enough for working in tight places where you want some of the surround to be part of the composition, yet it's not so wide that everything looks distorted. At the same time, you can use it for the near/far wide angle look to good effect.
That's my $.02 on the matter. My usual walking around kit contains lenses of 24, 50, and 85 mm focal lengths, and I'm rarely at a loss for anything else. So if you're bound and determined to get some more gear, consider an 85 and a 24; but don't go for the cheapest you can find. Get the original Canon lenses even if you must delay the purchase while you accumulate the necessary funds. They will serve you well over the long haul and will not disappoint.