I just use a hypoallergenic fragrance-free hand lotion. Cheap and gentle, and washes right out. It's lasted for me up to 70 mile long rides so far.

I've had some really sore sitbones on occasion....but never an open 'saddle sore'.
I'd say there was something definitely wrong if you are really getting saddle sores/open sores. But you didn't actually say you are getting open sores... being just really sore is another matter.