Are you in the Bay Area? The current band director at SJSU (who is fabulous; he taught at my kids’ Bay Area high school before getting his doctorate) is heading back to UMiami next year, where he did his PhD, to replace their retiring director of bands. I can guarantee the marching band program is going to be amazing! https://bandofthehour.miami.edu/ Of course, you’re not picking a school just for the band, but it seems to me that UMiami ticks several other boxes for you as well. Suburban campus, but great access to a major city. Coastal nature and, as you’d expect, great marine/enviro science opportunities. Diversity! (<40% white, although Asians aren’t as heavily represented as you’re probably used to out here, and Asian language/culture offerings are a little sparse.) A creative writing concentration in the English major (and there’s also an MFA program, so plenty of creative writing focus going on) English Major with Creative Writing Concentration| Department of English | University of Miami There’s club golf, too! It might be a little more of a party school than your ideal (1/3 Greek - but that means 2/3 aren’t!), but there are plenty of serious students, and some cool honors programs. Would likely be a low match for you (can’t really call a school with a sub-20% acceptance rate a safety, but I think acceptance is pretty likely, esp. if you apply EA).
UCSB CCS (a separate application in addition to the UC app) could be great for you academically Writing & Literature | UCSB College of Creative Studies, but the pep band there doesn’t march.
Vanderbilt?
Of course, U of Iowa is known far and wide for creative writing, and they have https://hawkeyemarchingband.uiowa.edu/
The BU marching band is relatively low-key but it does exist - seems like more of an urban setting than you want, but the academic variety is there for sure. BC also has a marching band and might be more appealing to you setting-wise, and they have a creative writing concentration in the English major.
The Weber Honors College at SDSU could be worth a look.
Good luck!