For starters, get a decent tripod!! I can't stress enough how important this is for landscapes. This will really improve the quality of your photos and you'll get the most out of your camera & lenses.
+1 for the 17-55 f/2.8 IS if you are not planning on getting a FF camera any time soon. It's a great lens!
Other options :
17-40L : not a fast lens but great for landscapes.
24-105L : ideal if you wanna have a single decent walk around lens. It has IS and a very useful focal range, especially on FF. On the 60D, its 24mm (38mm equivalent) isn't really wide tho...
24-70L : fast lens but again not so wide on crop, has no IS and rather heavy. Also the most expensive of the three.
A decent tripod and any of these lenses will set you back significantly more than just a basic kit lens. So I don't know if your budget still permits adding a 70-200 f/4 IS to all this. If not, the non-IS version is also pretty decent and a great bargain at half the price!!
50mm f/1.4 is pretty nice for portraits on crop and low light shots without tripod. It's also pretty small and light, easy to always have it with you.
Whatever you choose, buy your 60D "body only" or sell the kit lens immediately (if this makes more sense economically) and invest in some good glass, cause that is what matters for IQ.
Enjoy your new gear and don't forget to have some fun. Looking forward to see your favorite shots when you're back