You don't need an app.
A lot of my clients fret about this: Do we need an app?
They fret about this because a lot of other people (technophilic neighbors, "thought" "leaders") walk around telling other people they need an app, or asking if they have an app, or giving them ideas for apps.
You don't have to listen to them. That excitable guy at your fundraiser doesn't know anything.
You don't need an app.
Let's begin with what an app is and what an app is not.
An app is: A walled garden, a trackable download, a specific and tailored experience, a burden on your user, a hassle to keep updated, expensive to make, time-consuming.
An app is not: freely open and accessible.
"App" is short for "application". I assume we use the shortened form because it is cute. It is bite-sized. Contained. Approachable. For all I know, insidious marketers implanted it in our language because it sounds like Apple. I have no idea. (Though here are some interesting notes on the subject.)
But an app is an application just like Microsoft Office is an application. It is a way of applying the computing power in your hand to a task you need to do. It needs to have a purpose. It needs to DO something. It's in the root word! Your app needs to have an application. If you want to build an app for no reason other than it is sexy and new, let's just sit back. This is expensive. You'll now have to maintain your website AND your app. You must convince your user to download it and take up precious space and processing power on their phone that could just as easily be used for pictures of dinner, and cats, and bougainvillea. That's what matters to your users and you're forcing them to use your app.
You know what else is an application? Any CMS-powered website. Surprise! You already have an app! See, you're golden.
A tale of two conferences
DrupalCon does not have an app. That's probably because a) no one would use it and b) it's not very open, which just doesn't sit right with us open source types. The conversation at DrupalCon extends beyond the walls of the conference into every other person in the drupalverse. Anybody can follow the hashtag and see what's going down at the event, can chime in. Those who couldn't attend are included. Those without smart phones are included. Those who just hate apps (me!) are included. If you watch a DrupalCon session six months after the fact, you can still tweet about it and people will see it.
Dance/USA does have an app. It's actually a really good one, and they've managed to get people to use it (another reason why I usually advise against building your own app). The last time I attended the conference, there was a lively discussion happening on the app--it was, to be honest, like a private version of twitter with a few bells and whistles. But the thing is: I'm not at Dance/USA this year. I'm not even sure I am allowed to use the app. I've known people who had phones that were too old for it. So I get to follow a smidge of the conversation on Twitter but the rest is locked away. Why can't this discussion be available to the wider world of dance organizations? Why not put it on Twitter, which people already use and love?
Apps are not magic. They are not money-making magic elves (Well, actually, the money-making ones might be magic elves, but how many magic elves do you think you have in your organization?)
You don't need another app. You already have a solid web app that works on every phone. Stick with that and make it better.