First question is do you have a compact chainset(50-34) on at the moment? If not that would be the way to go, I have a triple and a compact and can get up the same hills on both, the ratio differance is not huge. If you go for a triple there is a slight drop in shifting performance as the middle ring has no stops, just the cable tension but set properly they work fine, weight wise there is not enough to bother with by having the extra ring!
A compact chainset looks much neater,no need to change any other parts and given time will get you all but the very worst of climbs. I am a stone heavier than you and can manage our 2.5mile, 850ft climb on the middle (39t) ring and 23t rear now but six months ago I needed a 30t-26t setup so go compact for the best of both worlds.