Need a easy drive speaker while I am traveling

Would closed headphone, in-ear monitors, or open headphones work?

or a car stereo?

I do  not use headphone, I will use it in the hotel room.

Be better to have small horn speaker or any other speaker.

I would just look into a good Bluetooth speaker like the offerings from Marshall, B&O or the B&W Zeppelin. 

That's the easy way, and just like directly from phone.

Second the Marshall Bluetooth speakers.

they are exceptional in the Bluetooth category