That's going to be a tough question to answer definitively. There are a number of classes of camera that could conceivably fit your bill, depending on how you weigh factors like size & weight, image quality, and cost.
Given the travel scenarios you described, you might not need a technical powerhouse of a camera. If you're shooting photos of buildings & people (especially during the day), a reasonably wide lens with moderate zoom capabilities is fine, and there are literally dozens of great cameras that can do this. I honestly don't see that your requirements dictate a DSLR at all - especially a prosumer model like a D7000 - especially when you include "lightweight" and "inexpensive" in the criteria.
Consider cameras like the Canon S95 or G12. The sensor isn't as large as a 4/3 camera like the G2, but it's better than a typical compact, and it'll produce very nice images in the types of conditions you're likely to see. They're all-in-one cameras, so you don't have pieces to keep track of when you're traveling, and they're very compact (how long is it going to take before you're tired of your D7000 taking up all of your carry-on luggage space?). You don't need a ton of zoom for buildings & portraits, so the 28-100-something lenses on these cameras should suffice. A larger range (especially on the wide end) could be helpful for some landscapes & architectural photos, but these ranges are right in the sweet spot you're going to be using most often.
If there are other factors that are pushing you toward larger cameras like the ones you listed, they're not clear to me -- perhaps more detailed scenarios would help.