Here is my “MegaWaltz”. All of the instruments (strings, pizzicato strings, flute, oboe and horns) are GPO.
The violins begin the initial melody. The cellos take the lead in their upper register at 00:40. The flute enters with the melody at 01:24 and is joined by the oboe dude with some harmony at 01:48. (Even though they are very different in their methods of sound propagation, flutes and oboes blend pretty well in a case like this.) The violins then return at 02:13. Flute and strings combine their voices at 03:56 and the oboe chimes in at 04:14.
I wrote a simple chordal accompaniment for the horns but they add greatly to the overall sonority, in my opinion. See what you think.
I blended one Gagliano solo violin with the violin section for the purpose of enhancement.