Purchasing 7D - please help with lenses!!!!

[Dr Croubie]

First off, my kit:
7D, EFs15-85, EF 70-300L, Samyang 35/1.4, EF 50/1.8ii, EF 85/1.8. I got the 7D, 15-85, 70-300nonL when I was still planning on travelling a lot (the 70-300nonL was nice and light, but I didn't like the IQ at 300mm so got the L after 6 months), then I picked up the primes variously when not travelling much anymore. Personally, i'd buy this exact kit again.

Firstly, 'normal' zoom options, as most people have said are:
EFs 15-85 - longer and wider than the f/2.8 lenses, if I could have only one lens ever, it'd be this.
EF 17-55 f/2.8 or Tamron 17-50 f/2.8 NON-VC (IQ of the VC is not as good) - get these if you want to do indoors shots, or people at night. Tamron is a lot cheaper, but less well built.
EF 24-105 f/4L - Only consider this in conjunction with an ultrawide-zoom. Only weather-sealed one here.
EF 24-70 f/2.8L - It's a brick, not a travel lens.
You mentioned taking photos at night, like architecture. For that, you want higher DOF and so f/2.8 isn't that useful, you'll be around f/5.6-11, and any of those lenses will be great there.

'Ultrawide' zooms (lots of options, best of the bunch are):
Sigma 8-16 (widest it gets, but slowest aperture, not that you need fast aperture for landscapes)
Sigma 10-20 f/4-5.6 (better IQ than the f/3.5 version, at least at 10mm corners)
Tokina 11-16 f/2.8 (fastest aperture, good IQ)
EFs 10-22 (best all-round compromise of the aboves, but most expensive)
For me with the EFs 15-85, i'm most considering the Tokina or Sigma 8-16. I can't decide (nor afford) hence I don't have an ultrawide yet, and in most cases 15mm is wide enough. If you go the 24-105 route, then the sigma 10-20 f/4-5.6 and EFs 10-22 become more viable options.

Long zoom:
EFs 55-250 - smallest and lightest of this list, IQ isn't so bad, and great value for the price.
EF 70-300nonL - nice and light, IQ at 300mm isn't so great.
EF 70-300L - Great IQ, smaller than the 70-200s, longer, weather sealed, and built like a tank.
EF 70-200L 2.8/4 IS/nonIS - non IS are about half the price of the IS version, but not sealed. f/4 are half the price of the f/2.8 versions. f/2.8 versions are not exactly travel weight/sized.
EF 100-400L - Longest it gets in canon-brand zooms, packs shorter than the 70-200s, costs more than 70-300L, and if you get a 17-50/55 you might miss a bit of length in between. Older than the 70-300L, not as good weather sealing and IS, but IQ is still up there.

Primes:
TS-E 17/24 - Great IQ, and purpose-built for architecture and landscapes. Too specialist and too expensive for my tastes, I highly recommend if you can afford them, but maybe hold off for after the trip, they'll take a lot of getting used to and practising.
Samyang/CanonL 35/1.4 - Both great IQ, Samyang better in the FF corners, canon slightly better in the centre, Samyang is manual focus only so not good for fast action, canonL costs 2-3x as much.
Zeiss primes - They're all great IQ, they're all manual focus, they're all expensive, they're all built like a tank, they're all heavy. I'd buy if I could afford, but maybe not travel-worthy.
Sigma 30/1.4 and canon 35/2 - Both great small travel lenses, but IQ is not the best, especially wide open.
Canon 50/1.8ii and 50/1.4 - The 1.4 is better wider-open, but has weird problems like coma. The 1.8ii is a bit of a 'my-first-prime' for lots of people (including me), can be sharper in places than the 1.4, nice and cheap and small.
85mm of various brands - only if you want to do portraits or indoor sports which you didn't mention. EF 85/1.8 is best value, but for travelling i'd leave it at home anyway.

hmmm, so where does that leave us?
the 10-20/22 + 24-105 is going to take more space and weight in your bag, but you get a weather-sealed normal zoom and biggest range. Changing lenses can get annoying, especially in adverse conditions (or in the presence of an impatient partner).
Any of the 15-85 or 17-50/55 will do you as good as each other. I'd go the 15-85 for landscapes, only go the f/2.8s for low DOF shots like portraits/indoors/low-light shots. For me the 15mm is wide enough for landscapes, I'd recommend holding off on an ultrawide zoom for now until you really decide you need wider (you can always stitch photos together to get wider-views).

For a long zoom, what do you want one for? Portraits, 70-200 f/2.8nonL. Walkaround 70-200 f/4 IS or nonIS. Best of everything 70-200 f/2.8 IS II with a few teleconverters (how deep are your pockets?). Birds and generally anything further away 70-300L or 100-400L.
For my money the 70-300L is the best travel compromise of length, speed, size, weight, and price.
But for you buying your first camera/lenses, I'd actually recommend the EFs 55-250. It's cheap, it's light, the IQ is really good for the price, it doesn't leave a gap if you get a 17-55, and unless you really really like birds or need a faster aperture it's really good value. You can always get whichever L later on, and not lose too much selling it.

Primes, i'd go the 50/1.4 or 50/1.8ii, although on a 7D they're a bit more of a portrait length. I highly recommend the Samyang for stitching panoramic landscapes (see my thread elsewhere), but it's not really a small/light travel lens (i'd agonise for ages if I had to travel and decide whether to take this), and not so useful for action needing auto-focus.
I'd actually just recommend holding off on anything wider than 50mm until you get to know your kit better.
The TSE 17/24 are of course perfect, but take some learning, and I personally wouldn't travel with them if i did have them.

Don't forget you need to budget for other things too. A good bag makes a lot of difference, I've got a Lowepro 350AW, fits a lot of gear (or some gear plus lunch/water/clothes) and a laptop/books. Tripod is highly recommended, especially for long-exposure, narrow aperture, low ISO night landscapes. My gorillapod SLR-Zoom with a simple screw-on Cullman ballhead is good for travel, but you can't always find a fence/post in the right location. Lightweight Carbon tripods are good for travel, like manfrotto 190-series (but they're not the tallest), 55-series are taller and a lot pricier.
You absolutely must get an RC-6 remote, especially for tripod-mounted shots. Best €20 I ever spent.
Also, a Circular Polariser, CPL, will make your photos just that much better. B+W MRC or the more expensive Hoyas are the ones to go for.
A flash is recommended, but not mandatory. If you get an EFs 15-85 with a flash, you can take better indoor group portraits than just a 17-50/55 f/2.8 by itself. Takes some learning, but well worth it.

also: Don't Forget Insurance!