I am going to travel abroad in a couple of months and I am considering, since I will take my photo-backpack with me (Tamrac evolution 8), to buy a diffuser for a Yongnuo 560 Mk III flash.
Most of the pictures that I will be taking with the flash are probably going to be of me and my parents, but I really dislike pictures directly flashed (lights too bright and shadows too dark) to the point that I would delete files from camera/computer.
Should I consider using a small softbox (and in case which one would be best for full-body and portrait pictures), or should I go for one of these plastic "caps" (which personally I don't like)?
Can you also suggest something that I can "re-use" for people photography?
EDIT: Even though I selected the most complete answer as the correct one (users who are yet to read will thank me... I guess), I still decided for a solution provided by another answer and got myself a portable softbox. This softbox kit has multiple uses, looks quite good in quality, can most probably be reused and is extremely portable.