The longbed seemed way too long for me, so I opted for the shortbed and have been happy. Yeah, the extra 12 inches or so with the longbed would be nice, and it would be cool to sleep in the bed with the tailgate up, but that comes at a cost. Here's a few measurements to think about as you consider the tradeoff:
Tacoma Doublecab shortbed wheelbase length/total vehicle length: 127.4"/208.1"
Tacoma Doublecab longbed wheelbase length/total vehicle length: 140.6"/221.3"
Chevy Suburban wheelbase length/total vehicle length: 130"/224.4"
I included the Suburban measurements to show just how large the 2005+ Tacomas really are. They are no longer mini-trucks by a long stretch (no pun intended). As you can see, the Tacoma Doublecab longbed has a wheelbase that is more than 10 inches longer than the Suburban, and the overall vehicle length is only 2.5" shorter. I used to think that Suburbans were enormous monstrosities, so I was blown away to discover that the 2005+ Tacomas are very comparable in size to the Suburbans. In my experience, wheelbase and rear overhang are the limiting factors with pickups offroad. Since the rear overhangs on both the shortbed and the longbed Tacomas are identical, and all of the increase in length with a longbed derives from the lengthened wheelbase (that is, the distance between the front and rear axles), the limitations imposed by a wheelbase that is more than 10 inches longer than a Suburban's should be the primary consideration as you noodle through your decision. Depending what kind of roads you wish to travel, it may not be an issue. Then again, it might, so choose carefully!
Another commenter said that the availability or nonavailability of the Offroad package with your desired configuration should not influence your decision. I tend to agree. I bought the Offroad package and have now come to realize that it wasn't worth it. The big draw with the package is the locking differential. The other stuff you get with the package is nothing special, including the Bilstein "offroad suspension," which bottoms out under any kind of load and is really lame. It'll be the first thing you want to get rid of, and if you're going to add a lift (highly recommended, especially if you go with the longbed), you'll be dumping the Bilstein springs, coils, and struts anyway, so in the end the only part of the Offroad package you'll end up with that's of any real value will be the locker. However, you can buy and have installed an ARB airlocker for a lot less than the cost of the Offroad package. The ARB is a better unit in my opinion, and is easier to use than the Toyota solenoid-activated unit, which I have found to be a bit finicky. Plus, you'll get a compressor with the setup and that's awfully nice to have.
These are my thoughts, but your needs and desires may vary from mine. Either way, you'll end up with a nice machine.
