I've mentioned this on another thread, but a friend of mine swears by the "earth friendly baby" nappy cream. Apparently, neither of her children have ever had nappy rash. She used to get it from Sainsbury's and its also available in good health food stores.
I use drapolene and then metanium for real nappy rash, so if these aren't helping, I'd suggest the above.
A couple of times ds2 has had a very sore bottom and I stopped using wipes and switched to warm water and cotton wool. Once the problem had cleared, I was able to switch back. I think sometimes their bottoms can become sensitised to the alcohol in the wipes. I also bathed him twice a day ( a pain I know - usually he's only bathed every other day) to give his bum a good soak.