Ballad Playing: a couple of harmonic trick I use (G. Perin) -V
Here is a couple of ways you can fill the space in between bars.
Those ideas could be use as harmonic or melodic device.
1. You can approach any chord with a dominant 7th chord built a half step up or down your target chord:
e.g. C can be approach with a Db7 or B7
I use this turnaround: C-Am-Dm-G7 and at the end I precede each chord with a dDom7 B7-C-Bb7-Am-Eb7-Dm-Ab7-G7.
2. Harmonize any given major or minor scale using a dim chord (G7b9) as a passing chord:
C6 - Ddim7 - C6/E - Fdim7 - C6/G - Abdim7 - C6/A -Bdim7.