We use an old Apple TV (2nd Gen I think) connected to a TV HDMI port. Tricky part is setting up local network to get your iPhone, iPad, Mac to communicate with the Apple TV. I had a small network controller (can't remember the brand) that I use for business travel in hotels to set up my own wireless network (gets around hotels that charge for internet by the device or limit the number of devices and also keeps your devices from seeing bad stuff from the hotel network). It acts as a router so the Apple TV and other devices see each other.
If you can afford the data charges you can use in iPhone for Netflix, etc. However this also alllows you to download videos to a Mac and play them back over AirPlay from the Mac or IOS devices with enough storage.I load up an external drive with ripped DVD's (fair use - I bought them I get to use them) and use my MacBook Pro as the entertainment center. I use RipIt as it gets around most DVD security issues. Ripping Blu-Rays is a whole different subject.
Those who are in the Windows/Android world can't use this but can use some of the other devices listed in other's posts.
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