Db Chord Progressions: Relative Minor Substitutions

Remember from last time:

I. Db major
ii. Eb minor
iii. F minor
IV. Gb major
V. Ab major
vi. Bb minor
vii(b5). C diminished

Each major chord in the key of Db has a relative minor that might sound great instead of playing the major chord, and vice versa. What? In other words...

I/vi: Db major could possibly be substituted with Bbm
IV/ii: Gb major could possibly be substituted with Ebm
V/iii: Ab major could possibly be substituted with Fm

Instead of playing I-V-IV-I, for instance, try the following permutations (not an exhaustive list), but we'll start with the original progression:

I-V-IV-I: Db Ab Gb Db
I-iii-IV-vi: Db Fm Gb Bbm
I-V-ii-I: Db Ab Ebm Db
vi-V-IV-I: Bbm Ab Gb Db
vi-iii-ii-vi: Bbm Fm Ebm Bbm
etc.

Substituting a major chord with its relative minor (and vice versa) might liven up a boring progression with a less boring progression (albeit still widely used).