To paraphrase the saying about paranoia: just because you're obsessed with battery life doesn't mean that data-hungry apps aren't out to drain you.
In my case, I decided to put my foot down on the issue of having to charge my phone at 2 p.m. every, single, day. I looked into the services running on my Android phone (a Galaxy Nexus), and noticed that those using up the most memory, and probably demanding a data connection most often, were Facebook and Twitter. That makes sense, as they are both services that want to ping or buzz you the moment you get a Like, Comment, Reply, Retweet, Favorite, Message, Invitation, Direct Message, and on, and on.
You can scale back how often Twitter checks for replies and messages, but not so much with Facebook. And in both cases, you probably want to know when you get a direct message through those networks. This moment, when you're wondering what compromise you can make between awareness and battery life? This is when I would tell you to load up Facebook.com or Twitter.com in your phone's browser, and notice just how functional and they look lately.
Facebook and Twitter generally have to keep their mobile webapps in decent order. While both firms would prefer a full on-device, contact-connected, instant-access experience with each user, there are large parts of the world where different phone platforms rule the market, or where older phones are the norm, or where devices without official app stores are sold. To give users most of the experience of browsing a stream, posting something new, and checking messages, they build much of an app's function into a reasonably interactive mobile site—even that nifty little "Pull to refresh" motion at the top of a stream.
What you can do, then: remove the Twitter and/or Facebook apps from your phone, then bookmark the mobile versions of Facebook and Twitter on your phone. On an iPhone, you can tap the box-and-arrow "Share" button and choose "Add to Home Screen" to create an instant, very nice-looking shortcut to the mobile webapp. On Android, in Chrome or the older "Browser," you'll need to bookmark the page, head into the Bookmarks section, then press and hold on the bookmark and choose "Add to Home Screen."
But what about messages? You'll want to head into the settings of both Facebook and Twitter on the web and make sure you receive an email for each message/direct message. Then, in your email client, do what you can to make sure messages from Twitter and Facebook get the notification/star/priority treatment. That's how I handle the disconnect, anyways.
I haven't had a Facebook app on my phone for more than 2 months now. If I really want to trawl baby photos and friends' jokes, or post my own little something, I can take a few extra seconds (if that) and load a nearly complete version in a browser. And I'm this close to making that switch with Twitter, too. It's not for everybody, and not everybody needs it. But the web can still be a really useful place, even when you use it like an app.