Panasonic DVD-LA95 9-Inch Portable DVD Player
Still the best there is
Trust me when I say that I looked at just about every portable DVD player on the market before deciding on this one.  Yes, this Panasonic is relatively expensive and you can find much cheaper alternatives.  However, the Panasonic has the best picture out there and a very large screen size to boot.  Plus, the external speakers on the Panasonic are head and shoulders above anything else out there, especially for watching and listening to the unit in the car.  The unit is very thin and light weight so you must be careful with it as with any portable DVD player.  I recommend the well-padded Targus bag which converts to a seat mount in the car.  Very cool, although it costs about $60.<br />In terms of battery life, I would say that you can get about 2 hours out of this thing, but not if you have it at the brightest screen setting and not if you have the volume turned up all the way.  You can also buy an external Panasonic battery which mounts to the bottom of the unit for an additional 2-3 hour battery life, but this things costs close to $200 so I haven't done that yet.  For the car, you can either buy Panasonic's car adapter ($100+ for some reason) or buy a power inverter from Radio Shack, Best Buy, etc. for about $40.  The inverter will allow you to plug the AC adapter that comes with the unit into your car's DC cigarette lighter.<br />After using this unit for a couple months, I can highly recommend it to anyone.  Yes, it costs more than most, but you get what you pay for.  This thing has been great for taking my 1 year old on long trips to visit relatives.  It's also good to bring with you to restaurants in case the little one gets impatient.  Plus, you will get a lot of compliments from the restaurant staff and other patrons who tell you it's just about the coolest thing they have ever seen.