Haydn Seek

I've been looking around the internet (albeit not very energetically) and I can't seem to find the answer to my question:
Is modern classical music defined by its 'unconventional' uses of tonality? Eg. is it possible to write a Neo-Classicist piece in functional harmony, and rely on other elements of the composition to make it modern, or is the use of tonality as a device rather than as a structural element essential?

Sorry this question is so specific! I just thought it'd be easier to ask than to spend my life trawling the web.

I'm not really sure if brass band music counts as exactly 'classical', but my old teacher/conductor has asked me to write a review for the local paper about a concert his band are doing. It's part of the 'Festivities' so there should be a good audience etc.

I was just wondering if anyone in this group knows anything about music jounalism? Any help is good, even if it's just an opinion. It's not going to be a long piece, obviously, and I don't have all the details yet, but any pointers anyone might have would be really useful. For example, what would be the best way to start/end such a review?

Thank you