Find out who you'd be riding with. If they're aggressive and want to ride fast, then look for a road bike. If you just want to put on some miles at a reasonable rate, socialize, and stay comfortable, look at a hybrid. I have an old Cannondale hybrid that I keep around for rides with the kids and party rides, but I have a specialized diverge for rides by myself that I just want to focus on riding.
If you go the hybrid route, staying under $1500 is easy. The road bike is a little trickier, but it can be done.
As far as features, disc brakes are nice but to go full hydraulic disc requires a little more maintenance than the mechanical disc.
Cannondale has a nice feature with built in sensors that you can sync with your phone to track speed and miles and the like. Saves having to buy a separate system. I'd assume that other manufacturers do this as well, but I've only been looking at the Cannondales as I'm looking at replacing my old one.
And you can definitely spend a lot of extra money to drop a little weight on a bike. Unless you're really competitive, it doesn't matter nearly as much as how comfortable you feel on it.