The typical attractive energy is around 20 kJ per mol. Note that this attractive energy quite high compared to other Van Der Waals forces such as dipole dipole and dispersion but still less than covalent bonding.
Attractive energy is just a determinant of the relative strength of a bond in relation to the energy required to break it. The higher the dissociation energy of a bond, the stronger its attractive energy is.
I don't think that attractive energy determines the structure of the entire molecule. Attractive energy refers to the strength of the bond. Hydrogen bonds are stronger than Van der Waals but weaker than covalent.