Become friends with the coaches. When those guys start rooting for you (and your kids in front of the their athlete friends who aren't in band) the kids really will start to feel more valuable as a band student.
Put more stock into your public performances (especially halftime). Treat your job like a Public Relations specialist. Who's your audience, how do you reach them, what's your goal with your performance). For example, our playoff halftimes are huge in that area for us...we ham it up hard, and have a lot of fun and the crowd responds to it!!! Put together a travel band (leadership only... or 20 kids who love band and don't do anything else), take them to a few volleyball games, perform for chamber of commerce events, etc. And sell your program.
Last, and I know it's hard...but keep "Bubba Football Fan" in mind when you pick your marching shows...know your audience. Your kids will buy in to your marching goals if your community is buying in.