Hmmm, landscape, portrait, macro with a budget of about $ 1200. You already have pretty comprehensive and wise comments here. So I’d just like to add my 2 more cts.
Selecting a lens is always a matter of compromise. And never an easy process, even when you’ve got the big bucks. A 24-105 becomes a 38-168 on a Rebel. As said, you might miss on the wide end as 38mm is relatively tight for landscape where 24mm is a real advantage. Meanwhile, don’t expect a huge difference between say 168mm and 135mm. Actually, a little cropping in post-processing can easily bring back the difference.
Honestly, and as suggested above, the EFS 15-85 would fill the bill nicely. It’s a sharp, contrasty and well-built lens. It covers 24-135mm on Rebel. For landscape and casual shots, it’s near perfect at the price point.
Since you’re left with some cash compared with 24-105 + 50/1.8, I would really suggest you to have a look at the EFS-60mm/2.8 Macro. You see, upgrading to DSLR from point-n-shoot provides an opportunity to change the way we approach photography. To grow.
Give your wife and yourself a treat : take the EFS-60mm. This will blow your mind and totally open new opportunities to both of you: macro, portrait, landscape, low available light … You’ll see, that lens may eventually stay on your Rebel more that 50% of the time. This is the kind of lens that makes the difference between DSLR and P&S. The kind of lens that makes the upgrade worthy. Later, when you become addict, like some of us here, you will drool for much more expensive stuff, I can tell you...
For now anyway, I would think a combo 15-85 + 60Macro would make a little more sense than 24-105 + 50/1.8
