Were I going on a trip with only 2 lenses... it might well be the 10-24 and the 56
Regarding the 14 vs the 10-24... You get wider with the 10-24. I love it at 10, even if I later crop it to closer to 12 or 14. In faster moving situations, sometimes there is not enough time to move and compose, especially in tight places and in crowds. You can always crop a little, but you cannot add.
also the 10-24 can get sharp results in lower light due to the OIS. The 14 is only 1 stop faster in aperture but the OIS will still give 2-3 stops better handheld performance. I've tried longer exposures handheld with the 10-24 and never expected them to come out and was surprised at the results. Under the right conditions, the OIS works wonders.
Without the OIS, I'd rather have the new 16 than the 14... because of the 2 stops faster speed. (Haven't actually tried the 16 yet). I'd also prefer the 16 over the 14 because of the weather sealing and though the 14 does good for close focusing, the 16 is even better.
I don't find the size weight differences significant compared to other considerations. Particularly taking only 2 lenses.