I don't like the 10-22mm and 15-85mm combination.... With only a couple lenses in your kit, that's too much overlap. If it were me, here's what I'd do....
1. Get the 10-22mm USM ($650 new, $500 or less used... plus lens hood $32 OEM, $20 3rd party... Total $520 to $680.)
2. Sell the 18-55mm (you probably won't get very much money for it, likely less than $100, depending upon version. The IS is newere & better than the non-IS version. The STM & IS version is newer & better than the IS version).
3. Buy a used EF 28-135mm IS USM. There have been so many of these sold in kit that they're pretty easy to find lightly used for around $200 to $250 US. This really isn't a kit lens, but an older design that still works quite well. It rivals the far more expensive 24-105L ($1150 new, $700+ used) for image quality and performance, just isn't as well built or sealed. I have two of these lenses... one cost me under $200 with OEM lens hood. The other cost me $250 with OEM hood and a high quality, 72mm filter (about $75 worth).
I'm pretty confident you could do all the above for well under $1000 and have a pretty versatile 2-lens kit. I figure between $720 and $930, depending upon how you buy and the deals you find. If you sell your 18-55mm kit lens for a few $, that would reduce your total cost a bit. As I recall from your earlier posts you had a budget of around $1000 total.
If you also want a "portrait/low light" lens, add an EF 50/1.8 II for around $125. Or even better, get an EF 50/1.4 USM, which sells for about $340 new (on sale now at B&H Photo), $300 or less used. Add another $15 to $26 for the ES-71 II lens hood, if it's not included. (Note: WIth this lens you must get and use the lens hood. When shooting it protects the front barrel from bumps. When stored in the reverse position, the hood covers and protects the focus ring. This lens is known to have a fragile focus mechanism, but seems to do just fine if it's given these reasonable and normal protections. It's also recommended not to do a lot of manual focus overriding of AF with this lens. My copy of the lens is 10+ years old and still going strong.)
The 50/1.8 II is a good entry level lens. It's capable of quite nice images and is a useful introduction to using a large aperture prime lens. But it is very lightly built and plasticky, and it's auto focus is slow, noisy and somewhat inconsistent. The 50/1.4 has incrementally better image quality, the differences are subtle, but it has less flare, better contrast, better color saturation, nicer background blur. Probably more importantly, it's AF is much better even though it's an old design and a hybrid form of USM.
The zoom lens combo above would give you pretty thorough coverage from 10mm to 135mm, which is actually more than most film photographers ever enjoyed with their SLRs back in the good old days. Many of them got a 50mm lens with their camera, added a 28mm wide angle and a 70-210mm tele zoom. That was a very common kit. On your T3i, 10mm to 135mm is equivalent to 16mm to 216mm on film/full frame.
Now, I don't mind carrying a camera bag with a few lenses.I do all the time. However, traveling you might prefer to only carry a single lens, for convenience and simplicity. The EF-S 15-85mm USM IS would be a very nice choice for that. It has excellent image quality and very good all around performance. It's a $700 lens new, or about $550 used. The EW-78E lens hood for it sells for another $15 to $30.
While the 15-85mm is a very nice lens, quite wide at the one end and covering ideal portrait short telephoto focal lengths at the other end of the zoom... There's a big difference between 10mm and 15mm wide. And 85mm is not typically going to be long enough for sports. (135mm is better, but really isn't long enough either, so either way you should start saving up for a longer lens.)
If you are in the US, I'd suggest looking at the larger online retailers (Amazon, B&H Photo, Adorama) for new items. For used, those also work, plus there is KEH in Atlanta. Also check out the Canon online store. There are sometimes refurbished lenses there, too. Refurbs and used from these sources usually come with some sort of warranty. Sometimes it's every bit as good as a new item warranty, other times it's a bit less time.
Locally, for used items check on Craigslist... but be very careful. Only meet in a safe place (inside a bank lobby or busy coffee shop), take your camera and test anything to be sure it's working, before handing over any money. There's no warranty buying this way!
A third possibility... if you didn't have a lot of use for it after your trip, you could rent a 10-22mm for those Vegas and LA visits. However, I think you mentioned previously an interest in landscape photography and ongoing cityscape shooting.... both of which suggest to me that you will want to buy that lens rather than rent it.
Hope this helps!
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Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories
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