My wife is also 5'6" and loves her x-lite. I have the men's version and use the 72" size which is just the right length for me. We've found them very comfortable, and the weight and small pack size are awesome. Both of us sleep stretched out, so we find the longer pad is worth it. About 20 nights on them since we bought them, and not a problem. I have an original Thermarest that has very frayed edges but still has never had a leak after 35 years!. My wife used it until we got the x-lites. They've been well enough insulated for snow for us, too, though we both are warm sleepers. I move around a lot and when I used a short pad and pack, the pack ended up migrating and my legs dangling. I'd have to get up and rearrange the furniture. At 8 oz. they were light enough and pack small enough to warrant the extra length for us. I tried various pad / combinations trying to reduce pack size, but always opted back to comfort. The neo-airs seem to allow both. The 66" women's model has a greater r-value (3.9) compared to the regular men's (72") at 3.2.