The WTB Pure V seems to be a universal favorite. Some Bianchi bikes now ship with this type of saddle and they are very comfortable.

http://www.wtb.com/products/saddles/performance/purev/

My skinny 17yr old DS uses a WTB SST on his daily rider. It's the stock saddle that comes on a LHT. Our local bike shop had so many in the extra parts bin they gave it my DS for free. He swears it feels fine - and there is no way he is going to let his mom measure his sit bones..lol.

http://www.wtb.com/products/saddles/saddles-sst/