If there are 3 of you driving 3 1080p streams then its going to be tough. All I know is that on my network, there can be 3 people netflixing at the same time ( in addition to other people doing regular surfing) and each person, even when they're the only people on the network only use 2mbps.
I know for a fact that everyone who netflixes here only watch on laptop screens. Only one girl chromecasts (which I highly recommend). There are some buffering issues, but it's seven people on 7.5mbps. It's not going to be perfect. But for a line that is managed by me and for a stupid low cost that they wouldn't know how to get for themselves, they're happy to pay $6/month for internet.
Now considering that you and yours can determine how much you want to pay, I recommend that you get at the very least a high end router that has a FAST PROCESSOR. Don't confuse this for fast wireless. Fast wireless is pretty useless when all you are considering is surfing performance. 750mbps antennas are useless when your service is only 30mbps. Even wireless G is still fine for these speeds (and is what I use as cheap antenna extensions to dead spots.
Get a router with a fast processor that you can flash 3rd party firmware on. (for future proofing)
Lots of speed, lots of memory. If you're not smart with networks, this will circumvent 80% of all your 'internet speed' problems.
It's one thing to choke the internet connection, but usually you've choked the router, and buying a faster internet connection doesn't solve many problems.
If you install 3rd party firmware on your router, you can start to see who, and WHAT is the real problem.
Also with 3rd party firmware, you can see how much speed netflix really requires, and what you might see is that netflix to one computer blasts a whole bunch of data to a computer, then is idle for 3 seconds, and blasts again, repeat. So with this on/off cycle, you could theoretically have 2 5mbit movies running on a 5 mbit line. So instead of on/off/on/off/on/off activity on your router of one stream, you can see that you're having on/on/on/on/on of 2 streams.
My router has a 480mhz processor and 128mb ram (asus rt-n16) Perfectly fine for your 3 person network. It's $100. If you want to get something better there's the asus rt-n68
The only thing you want to focus on is processor and memory. Of which the n68 has a 800mhz processor and a 256mb of memory. Those are the only two features that matter when it comes to network harmony.
So yeah, start with good hardware, and the slowest speeds and only move up once you know why the internet seems 'slow' It only takes one hog to kill a connection, and it's usually not netflix. It's usually P2P programs. You don't have to torrent either. Did you know that Spotify was a P2P network?
How do I know this? I installed tomato on my router and when the connection craps out, I know who it is and I can do something about it.
It's the reason when I asked everybody to upgrade their service form $6 to $7.50 each, everyone said no, it works fine.
7 people on a 7.5mbps network don't want to pay $1.50/month extra for a 25mbps. That says something.