Hello, I am new to using forums, but I have found them useful in solving some problems with technology so I searched for this current problem. I recently just upgraded to the s5 from an iPhone as well and have been both very pleased and very frustrated. This problem was one of the worst. I think that I may have stumbled upon a solution that is not ideal but definitely "liveable"

IF you have verizon...
If you remember when you first got your phone and it was preloaded with all these random apps...one of these was the Verizon messages app. It is not the prettiest of texting apps and the layout of the other message app does work and look much better, BUT the Verizon message app does allow you to send multiple pictures! Up to 7!!! You can select them both in the message app or in the camera app. Selecting them in the camera app first all at one time is much faster.
Once you play with the settings of the Verizon app it can be much more easy on the eye . It is a bit glitchy but with my friends and family I send pictures quite a bit so I can live with it. Anyway, hope you see this and hope this works for you!!!
On a side note...my other major switch problem has been playing music through my truck radio. My iPhone would work perfectly through the usb port but the s5 will not seem to play. Any thoughts? I have tried an a/V cable also and no luck. Anyone else experienced this? Music through the radio is so nice for road trips! Thanks!