Thanks very much. Again, I'm not looking for a perfect all-around lens. You're right that the Canon 15-85mm is relatively expensive, but it does seem significantly sharper than the cheaper options (e.g. Canon 17-85mm, Sigma/Tamron alternatives, etc.).
I only have my limited experience with no more than 55mm focus but my impression is I don't need more than the 85mm as my all-around longest focus. Maybe I'm wrong. I get the impression that smallest focus of 24mm is too long or at least borderline. I did use 18mm or slightly more for some shots where moving further away was a problem (for technical reason, not landscape photos). I don't think I need the 105mm of the 24-105mm lens since I plan on buying a 100mm prime/macro lens anyway.
So the question really is, for what I need, do I have a better alternative than the Canon 15-85mm lens? I came to my own conclusions, but being a beginner, maybe someone here can find flaws with them that I missed. Keep in mind my main goal is the instruments and getting sharp photos of them and that I want very sharp photos for my website and possibly other situations, I'm not looking to become a photographer. Low light situations are a lower priority.
Prices here are significantly higher than in USA and I don't want to risk ordering from out of the country (expensive returning if necessary). Used is possible but hard to find, is relatively expensive too (obviously) and it's not so uncommon for people to say something is in great condition only to find there's a problem after you buy it... Coming from the musical instrument world, I constantly see people buying a used instrument in "great" condition only to find it needs a lot of repairs. So it's a bit of a risk. I don't think I'll spend more thand $1,000 local price. I'm leaning strongly towards Canon because I've heard abotu too many QC issues with Tamron and Sigma from local photographers.
Anyway, prices here for the lenses mentioned:
Canon 17-85mm f/4-5.6 IS USM - $600 (found used for about $350-$500)
Canon 17-55mm f/2.8 IS USM - $1,500 (haven't found used yet)
Canon 15-85mm f/3.5-5.6 IS USM - $1,000 (haven't found used yet)
Canon 24-105mm f/4L IS USM - $1,400 (found used for about $900-$1,000)
Canon 24-70mm f/2.8L IS USM - $1,800 (found used for about $1,200)
Tamron 17-50mm f/2.8 VC - $800 (haven't found used yet)
Tamron 17-50mm f/2.8 (no VC) - $600 (haven't found used yet)
Tamron 18-270mm f/3.5-6.3 VC - $850 (found used for about $550)
Canon 10-200mm f/2 - $999,999 (found used for $999,998)