  Quantum phases and phase transitions of weakly- to strongly-interacting
bosonic atoms in deep to shallow optical lattices are described by a {\it
single multi-orbital mean-field approach in real space}. For weakly-interacting
bosons in 1D, the critical value of the superfluid to Mott insulator (MI)
transition found is in excellent agreement with {\it many-body} treatments of
the Bose-Hubbard model. For strongly-interacting bosons, (i) additional MI
phases appear, for which two (or more) atoms residing in {\it each site}
undergo a Tonks-Girardeau-like transition and localize and (ii) on-site
excitation becomes the excitation lowest in energy. Experimental implications
are discussed.
