"Always" doing something - difference between 一直，总是，老是...

Hey guys,

This has been been confusing me. I am never sure when to use 一直，总是 or老是... I have learned by now that 老 is often being used when something has a negative connotation. But what to use for the following:

I have always been very tall.

She always knows where to go.

They're always talking in class.

I've always wondered ...

He's always smiling.

Does anyone know a good way to distinguish between those?

安东