I use a mountain frame with front shock, front disk brake, seat post shock and 1.5 in tires for road work and 2.0 tires for "trail" work. I don't do off road riding.
The 2.0 tires are the Schwalbe brand which are quite puncture resistant.
I both tires, I use the self sealing slime tubes.
I have both front and rear panniers and occassionally, I also hook up a BOB tailer. I use the trailer when I am carrying camera equipment. I put the camera stuff in the trailer, as I have the panniers all organized the way I want them.
I like the MTB frame because I am sitting more upright. I find that that position is more confortable for long trips than the position required for the more traditional road bike.
I also like the MTB frame because it seems to handle the large load I carry. My bike, when loaded with 10 plus liters of water, tent, food, sleeping bag, clothing, chair, table (not a joke, I carry both) stove, water purfication, jackets, etc, is about 170 pounds. Than add my large self, I wanted a frame that handles it.
All of this easily fits into two duffle bags for airline travel. The bike fits into a large bike box I got Nashbar.
The MTB frame with shocks requires you to compress the shock to fit in. Or, you must remove the rear deraillier, in addition to the seat, handlebars, etc.
For travel in the US, my wife and I put our bikes in the back of a private airplane (after removing the wheels, pedals and seats.
I guess that most any bike you are comfortable with will work for touring. You will have to modify it to your taste and experience.
My Trek is 13 years old. The only thing original on it is the frame.
In summary, I would not go out a buy a "touring" bike. I would find a bike I enjoyed riding and modify it so that it is comfortable to ride while touring.
Regarding panniers. I would not buy inexpensive panniers. After a couple of years you will realize why they were cheap and hate it that you wasted your money.
I used some Cannondale panniers for over 10 years. Four years ago, I bought some Arkel panniers and love them.
My wife likes her Jandd panniers. My sister likes her Ortlib.
I hope that this rambling is understable and helps your decision making.
Tom