We are planning a trip to Scotland this winter. My husband and I are both bringing our cameras and are trying to save space by combining our respective camera bags into one (with the hopes that the other can carry-on our clothes and avoid checking bags). He is only bringing one lens - the kit lens for his (my former) Canon Rebel XTi. I'm trying to decide what to bring for my Canon 1Ds. I have a 50mm, 28-200 and a 70-300. I'm totally open to buying a new lens (any excuse for new glass, right lol) and have received suggesting to pick up a 24-70, 28-105, 100mm, and a 100-400.

So, now I ask you guys... what is the best and most versatile lens for New Years in Edinburgh?