Lens suggestions for noob's photographic needs

Also, any thoughts on the 17-40L for my purposes? It's a "bargain" L lens, and I've already written about how I was impressed with the 24-105, so I'm guessing I'd get similar quality?

I know it's probably slower than ideal wide open for indoor photos, but then again I was fairly pleased with the f/4 ISO 800 shots I got with the 24-105. Plus if I get a flash as others have suggested, wouldn't that also help with the indoor photography?

Wow, so many different ideas. If family pictures are at the top of you list, you already have a great portrait lens, the 50mm f1.8. To supplement that for outdoor portraits I would add the
Canon 85, f1.8. I hadn't thought of a flash, but that is an excellent idea. Perhaps a 400, 500, or 600 series Canon flash- would look for a used one to save money. You would still have money left over for a 55-250 for those other type of pictures. The only disadvantage I see with this set-up is that one day you will probably want to replace the 55-250 with something better, though you wouldn't have spent that much on it so you won't lose that much on it either if you sell it. If you want to start at the top, then keep what you have and add a Canon 70-200L f4 IS or a Canon 70-300L IS. Neither of those would be a first choice for portraits on a crop body, especially indoors, but they are both great lenses which I'm sure you will enjoy and will hold their value if you ever wish to sell them.
If you get the flash be sure to visit the site that stsva linked to, and buy his first book too. Lastly, forget about the 24-105L unless you go full frame.

Bearmann wrote in post #14952000
Wow, so many different ideas. If family pictures are at the top of you list, you already have a great portrait lens, the 50mm f1.8. To supplement that for outdoor portraits I would add the
Canon 85, f1.8. I hadn't thought of a flash, but that is an excellent idea. Perhaps a 400, 500, or 600 series Canon flash- would look for a used on to save money. You would still have money left over for a 55-250 for those other type of pictures. The only disadvantage I see with this set-up is that one day you will probably want to replace the 55-250 with something better, though you wouldn't have spent that much on it so you won't lose that much on it either if you sell it. If you want to start at the top, then keep what you have and add a Canon 70-200L f4 IS or a Canon 70-300L IS. Neither of those would be a first choice for portraits on a crop body, especially indoors, but they are both great lenses which I'm sure you will enjoy and will hold their value if you ever wish to sell them.
If you get the flash be sure to visit the site that stsva linked to, and buy his first book too. Lastly, forget about the 24-105L unless you go full frame.

I do love the pics I get with the 50mm. I have thought of adding another prime, but I was thinking the other way - wider. I have found that when I'm shooting with the 50mm indoors OR outdoors, there have been more situations where I end up having to step back to get the shot I want vs moving closer.

That being said, I can only think of 2 primes - the 28mm 1.8 and 35 mm f/2 that are wider than my 50 and also fit in my price range... would either of these be a good addition, or would I just be paying extra for only a marginal improvement in IQ over what my 18-55 kit could do in terms of focal length? If that's the case I wouldn't mind considering the 85mm as I could see that giving me some flexibility and more creative options

the primes will be much sharper than that kit lens. That kit lens isnt too bad, but primes can be easier to work with. I recently went to a wedding and instead of worrying about the 18-135 I went with the 24 2.8 and it worked perfectly. The 35 2 is quite good as well. It sits in my bag most of the time until I absolutely need it, but when I need it, it works great.

Here is the 28 f1.8: http://www.photozone.d​e …25-canon28f18apsc?start=1
Here is the 35 f2: http://www.photozone.d​e …57-canon_35_2_50d?start=1

I have mixed feelings about these two old war horses. The bokeh of the 35 looks terrible, not something I would want in a portrait lens. The 28 is sharp enough in the center. If you are doing a single portrait (in the center) the edge blur is probably fine and may even be desirable.

The Canon 17-55 is a consideration: http://www.photozone.d​e …non_1755_28is_5​0d?start=1
but I'm not sure the f2.8 aperture will be wide enough for you on a crop. You could also consider the Sigma 17-50 f2.8 previously mentioned at a significant savings to the Canon. I'ts sharp in the center at f2.8 and again, the blurry edges may be desirable. You can begin to see why portrait photographers usually migrate to full frame cameras for that very narrow depth of field. A f2.8 on a full frame would be between f4.0 and f 5.6 on a 1.6 cropped sensor as far as DOF is concerned.

I would consider the new Canon 40mm pancake, though it's only f2.8 and only slightly wider than your 50mm. It's sharp at f2.8 though, which is it's claim to fame, along with it's price.

This leaves the Sigma 20mm f1.8 and 30mm f 1.4 and maybe some Tokina or Tamron selections. I'm not real familiar with these two lenses, but I think the 30mm is well regarded. Probably worthwhile to do some homework on these two.