Rooting is truly a personal preference, and since you've done it before, you already know the advantages and disadvantages. I wouldn't do it just to install a custom ROM, as JB is quite nice as is. But for purposes of using something like Titanium Backup or just to have more access to the OS and feel like an Android god, maybe it's something you'd want to do. There are lots of utility apps out there that require root access for full functionality. Plus, you can use a USB flash drive with the StickMount app to expand storage (see non-root alternative below). If you play lots of games, you can also use a game pad controller via Bluetooth, using the Sixaxis Controller app, which requires root.
To really customize and get more out of the interface, install an alternate launcher. I really like Nova Launcher Prime, but then again, it's the only alternative I've ever used. Also, test out some alternative keyboards. I like SwiftKey for Tablet, but there are a ton out there. Of course, you might like the stock keyboard just fine.
To fully utilize the camera, get the free app Camera Launcher for Nexus 7.
You'll want a versatile media player like MX Player or BSPlayer. For music, I like n7player and jetAudio Plus, but there are many from which to choose. If you don't root, but want to attach a USB flash drive for media copying or streaming, then I'd recommend the Nexus Media Importer app.
Easy Voice Recorder is a good audio recorder, as is TapeMachine, though only the paid version is worthwhile.
If you have DirecTV at home, I definitely recommend DirecTV Remote+ Pro. It let's you control all the DirecTV receivers around the house from your N7, no matter where you are in the world - great for messing with the family!
For a better calculator, get RealCalc. The free version is very good, and much better than stock.
Need a dictionary? I like WordWeb and Dictionary.com.
GrooVe IP lets you use your Google Voice account to make phone calls with your N7. I tried it using a Bluetooth headset and it worked!
Get a good file manager like Solid Explorer or ES File Explorer. These will also let you connect to your desktop computer within your local network to transfer files.
BubbleUPnP is great if you have a DNLA TV, as it allows you to wirelessly stream video and audio files from your N7 to your TV (or computer with the right software).
For printing using Google Cloud Print, I like the app Cloud Print. EasyPrint is also good, and for printing without Google Cloud Print, try PrinterShare, though it's a bit expensive.
Other utilities I like are Power Toggles, DiskUsage, Battery Widget? Reborn!, AirDroid, AndroSensor, GPS Test, Field Compass, OS Monitor, WiFi Analytics, Speed Test, Screen Test, and BTmono.
Also, download alternative app store apps. I have 1Mobile Market (go to their website to download it), Amazon (also have to download from their site), and SlideME Market. 1Mobile gives you access to apps that Google Play lists as incompatible with the N7, like CNN and USA Today, among many others. They usually work just fine and really aren't incompatible.
I'll let you figure out news, sports, technology news, weather, shopping, entertainment, language, health, reference, unit conversion, travel, financial, food, internet radio & scanner, earth & sky, creativity & office suite, calendar & task, cloud storage, social networking, and game apps on your own! Otherwise, I'll never finish this damn post!
Sent from my Nexus 7