I've just tried Eucerin the last couple of days. It's better than petrolium jelly. I feel the moisture just seep into my skin. It's not hanging out on the outside like the other jelly. It's greasy for about an hour or so but no mushy armpits.
The other night, I tried sleeping in just a big shirt. I'm a restless sleeper so I really move around in my sleep. In the morning, my legs were very dry from rubbing against the sheets. Then I tried wearing leggings at night. That seems to work. PJ's roll up to my knees so I'd be dry from the knees down.
One more thing I do at night is sleep with a humidifier. Keeps the skin moist. Especially inside your nostrils. It's not fun being dry in there. If you need more moisture, rub some lotion with a Q-tip.