I literally just got back (a few days ago) from spending a few weeks in Europe with my 7D, 10-22mm, 17-55mm, 50mm and 55-250mm. I too have little interest in portraits, and took a lot of landscapes, architecture and "detail" shots on my trip. And I left my tripod at home... so perhaps some of my experiences/thoughts will be useful...

I carried the 3 zooms around with me most of the time, occasionally taking the 50mm out, and if I wasn't really feeling up to carrying it all, I'd just take the 17-55. I remember at the time thinking the 10-22 and 55-250 were by far the most useful lenses, though oddly the proportion of all photos from each lens was:

• EF-S 17-55mm f/2.8 IS USM — 44%
• EF-S 55-250mm f/4-5.6 — 28%
• EF-S 10-22mm f/3.5-4.5 USM — 24%
• EF 50mm f/1.8 II — 4%

I've yet to sort through my photos, so if I remember I'll come back and update the percentages based on the photos I actually liked (; I'm quite sure the best will be from the wide and telephoto.

I remember thinking often that I'd have probably been happier with the 10-22mm and a better telephoto (70-200 f/4L or 70-300L), and just a 30mm in the middle (for weight reasons). The other thing I wanted was a second body... As much as I like my 17-55 (especially if it's the only lens I'm carrying), I have a feeling that two bodies, one with a good wide angle, the other a good telephoto, and a 'normal' (30mm for crop) prime in the bag, just in case, is all one really needs... but it's hard to justify a second body just to be switching lenses less frequently! But for travel or events, when lots of things are new and unexpected, it seems to make sense.

I found the 10-22mm great for the big old churches, even though the 17-55 has a wider aperture, 17mm just didn't cut it in some of them. I think a similar lens that goes as wide as 11 or 12mm would also be fine (e.g. Sigma/Tamron/Tokina offerings), but the 17 or 18mm wide end of 'normal zooms' wouldn't cut it.

The tele was great for odd details, especially interesting people (I'm not one to approach people to take a photo), a bit of wildlife and the like. Mine's the kit one I got with my 450D a few years back which I'm saving up to replace with something with a wider aperture, but even so it was very useful and sufficient quality at f/8 to f/16.

The 17-55 was most useful when I didn't want to carry a lot, since its kind of wide and kind of long, so I'd probably still take it again, (even if I had a 30mm prime), unless I was expecting to have all my gear with me at all times, and wouldn't be comfortable leaving it behind somewhere on shorter day trips.

So if you want to stick to 3 lenses, I'd suggest an ultra-wide like the Canon 10-22mm, a good tele zoom like the 70-200 f/4L IS USM (or 70-300 if you like wildlife which I usually find I'm wanting more than 250 for) and a 30mm prime like the Sigma 30mm f/1.4 HSM.

Edit: I guess if you're aiming for highest quality, I should be suggesting the 35mm f/1.4L instead of the Sigma.

Edit 2: In hindsight, with a bigger gap than I had between the wide and zoom (i.e. 22 to 70mm instead of just 22 to 55mm, you may be wanting more than just a 30mm or 35mm prime in the middle there... especially if you don't already have a 30mm and use it regularly enough to be comfortable with it!)