Possible simple and cheap/easy solution arrived upon!
Firstly, thank you to those with suggestions on devices--I did buy two things mentioned in this and another thread--a 5 USB port adapter and also the portable charger that is said to work on more than just phones.
As well, thanks for other tips in this thread. Turns out my devices includes the following and everything appears to check out:
Samsung Galaxy Tab 4 - 110/240
iphone 5s's - 110/240
iPad Minis - 110/240
new Mac Air my wife sometimes travels with - 110/240
The issue in this thread was how to solve loose plug problems typically found in hotels and on planes.
Fatter plug prongs could work and to make that happen if they exist somewhere, but while I look further for them, I needed to see what else could be done.
I did try to melt up a pool of solder and dip some plug ends into it, but I couldn't really make it stick.
But then I decided to test the use of simple kitchen tin foil! This you could bring with you in a small square and tear off a piece to wrap around the prongs of any plug. Now when you push it into the socket, contact is made but the looseness should lessen. I tested its actual use and ability to still be a working plug at my house and I am happy to report nothing has gone wrong--no shorts or fires. I had wrapped some tin foil around the end of the prongs of an extension chord and then plugged that into another one, and then plugged that into the wall. The fit between the two chords was tight and contact was made so charging could be done. I did it this way so that if any tin got left behind when pulling the wrapped prongs out, it would only affect the second chord, not my wall outlet.
I have not yet tested the tin plan on any outlets as all mine at home are good and not loose.
In the case of a hotel or plane, well, I will hopefully leave no tin foil bits behind, but if I do, then maybe this will entice them to get maintenance out on the job to replace the aging outlet anyway.
I will report back when home from Germany later in September.
MM