I used to think that all really high quality leather was lambskin or kidskin, and I certainly love both. But, the problem with leather that's so light and soft is damage. In fact, I've scratched lambskin pants simply by sitting on a rough wooden chair.
However, I recenlty bought a pair of calfskin leather pants made by Ari Soffer, who is based in LA and makes *very* high-end custom clothing and jewlery. Now, I can see that mid-weight [semi-thick] leather can be just as luxurious as lambskin, perhaps even moreso. The only problem is that it's extremely expensive. Given a choice, I prefer the calfskin leather because it's thick enought to withstand regular wearing without having to worry that sitting on a chair will scratch them