Apple’s next event is tomorrow, and we’re so excited we could drive down to Cupertino right now. For the first time in years, Apple could be unveiling a completely new and genre-defining product. Apple’s building some sort of 3-story high structure as part of this event, for crying out loud. This is going to be big.

We have a good idea regarding some of what to expect from the September 9th media event, but it still remains mostly a mystery. There will be iPhones—of that, we’re sure. There will be iOS 8 announcements. There will also be whatever it is that’s inside the temporary mystery building now standing next to Cupertino’s Flint Center for the Performing Arts. Here are our predictions for what’s going to debut onstage tomorrow.

iPhones, iPhones, iPhones

Since the debut of the iPhone 4S in 2011, Apple has regularly launched a new iPhone in early fall (usually September). With umpteen thousand supply chain leaks, insider gossip, and purported photos, there is no doubt that we will see a new iPhone on Tuesday. And this iPhone will likely differ significantly from its predecessors.

For starters, it’s going to be big. And possibly come in two sizes: a “smaller” 4.7-inch display, and a larger phablet with a 5.5-inch display. The smaller model could have a 1334 x 750-resolution screen while the larger one is expected to have a 2208×1242-pixel resolution display. That would mean the smaller device would be double Apple’s current Retina display resolution while the larger one would be triple, so scaling up graphics and designs would be fairly straightforward for developers. A one-handed mode will reportedly solve problems the larger size may cause regarding usability.

The display itself could be made of harder, more scratch-resistant sapphire, but Apple has reportedly had production issues with the new material (which it already uses in its Touch ID sensor). The larger size will also logically necessitate a mobile payment platform. Our sources said this system would incorporate NFC, which leaks and other outlets have also confirmed, but I suspect we won’t hear NFC uttered once in Tuesday’s presentation. Instead, Apple will have slightly adjusted this technology, or combined NFC with its Bluetooth and Wi-Fi-based iBeacon platform, so that it is a system completely unique to Apple. Visa, MasterCard, and American Express are reportedly on board with this mobile payments platform, and a leaked image of an iOS 8 Passbook icon now includes a section that looks to be devoted to mobile payments.

The new iPhones will also likely include upgrades to their cameras, like optical image stabilization (perhaps only in the larger model). Some schematics show the camera protruding slightly from the phone’s rear face.

Apple’s Long-Awaited Wearable

The biggest question of Apple’s Tuesday event is: Will the company unveil a wearable? Our hunch is yes, and both The New York Times and Wall Street Journal seem to agree. Apple will likely show off a prototype of its wearable design and how it will work, but it won’t ship for a few more months—early 2015 at the earliest—as there are no signs of mass production yet.

The details around how this so-called iWatch will look and function are fairly slim, but reports suggest it will include a curved OLED display and come in two sizes.

We expect it to integrate with Apple’s HomeKit and HealthKit platforms, tracking vital signs like your movement and heartrate while also letting you control Bluetooth LE devices in the home remotely. It will also reportedly perform mobile computing tasks like displaying maps, and run third party mobile apps.

While this is bit of a leap, the wearable could be targeted more at ladies than gents. Why? Many men are already watch-wearers, whether it’s a suit-compatible Rolex or sporty GPS watch, and a number of existing wearables are more masculine in design. Women are underserved in the fitness wearable space, yet they use health and fitness apps 200 percent more than men do, according to a Flurry Analytics study from June 2013. And Apple’s made a number of hires from the fashion world over the past year, so its wearable design is clearly a big priority, and something that needed outside expertise before coming to fruition.

The Experience: iOS 8

At WWDC in June, Apple highlighted some of the big new changes iOS 8 will bring. Tuesday, Apple will likely go over a number of these new features a second time, and give more detailed, consumer-focused demonstrations about how they work.

Expect to see iOS 8’s interactive notifications (in Notification Center, the homescreen, and the lockscreen), as well as updates to Mail, Safari, and Spotlight Search. I think Apple will also spend some time showing off its new iOS 8 keyboard, and at least one third-party keyboard—a new option previously not available in iOS. I’d hazard an Android favorite like Swiftkey or Swype may make an appearance onstage.

Apple’s new home and health-focused platforms, HomeKit and HealthKit, should also see some time in the spotlight. Perhaps that’s what Apple’s mystery structure is all about—a model home outfitted with all sorts of examples of how your iOS device can control and interact with household tech and accessories in an easy and intuitive way. (Or, it could just be a larger demo space to go hands-on with announced products after the presentation.)

Continuity, which syncs up iOS and OS X into a more seamless experience, likely won’t get detailed too much further until Yosemite debuts later this fall. Continuity will let you start an email on one device, and pick up right where you left off typing on another iOS device or Mac, and will let you take voice calls on your Mac, dialing over your iPhone and using the Mac as a speakerphone.

A Touch of iPods

The iPod audience continues to shrink, but Apple hasn’t cut the cord yet. However, we may not see much on the iPod front on Tuesday. Apple already updated the iPod touch this year, in late June. Apple usually redesigns the touch on the same cycle as the iPhone though, so we could see a new, slimmer form factor for the device. A good number of developers use iPod touches rather than a more expensive iPhone for testing their apps on beta software, like the current iOS 8 beta. iPod touches are also popular with kids and families.

What We Won’t Be Seeing

While there have been plenty of iPad rumors mounting, I doubt we’ll see new iPads at Tuesday’s event. Apple will likely save new tablet announcements for a later fall event closer towards the holidays, as it’s done in the past. Ditto for Macs: We probably won’t see any new desktop hardware from Apple this time around. Instead, we’ll see it later this fall when Apple officially releases OS X Yosemite. And while Apple may tease a few Yosemite features that work with iOS 8, I don’t think we’ll get a firm date for Yosemite at this point.