You have a good foundation for becoming quite a good arranger (ie. you have totally got the knack with the basics which too many people completely MISS !!). Now all you need to do is to expand on what you already know.
You have chosen your Instrumentation very well !! If i was to add anything (not that it needs it) i would use Vibraphone somewhere. For instance, if i wanted to EXTEND the piece i would add a ‘Solo Section’ and have Vibes being the featured instrument.
i like the solo trombone on the counter-melody (ie. rather that having 2 x horns playing in 2-part). i think the Trombone could be used on the melody-line in the B Section (say, instead of the Guitar). Then the Guitar can be TACET for 8 x bars (nothing wrong with the odd 8 x bar Tacet !!!).
i only had one quick listen and i think the last chord was Supertonic (chord) over Tonic (in bass). Might sound a bit ‘richer’ if you make this a Mixolydian Augmented chord. Don’t know your KEY, but if the last chord is a C Triad over a Bb Bass in the Key of Bb Major, then make it Bb13(#11) chord instead !! Up to you though of course.
Not sure about the title !! i might have gone for ‘Say It With A Kiss’ or (as your composition lends itself towards) ‘Goodnight From Broadway’.
Nice piece, as its my type my music !!!