Originally Posted by Fueled by Boh

I pretty much agree with duck, since you've got a trailer already. a mountain bike has its advantages off road, but when it comes to spinning on flats and paved surfaces, you might wish you had more "roadie" geometry and some higher gearing... if you think road touring is in your future, you might want to consider a bike like the LHT. The LHT with 26" wheels makes for an extremely versatile bike. It actually resembles some of Thorn's offroad/ expedition tourers.

I wouldn't recommend a suspension fork though. If you are touring off road, you'll probably stay away from real mountain bike trails and find yourself on more level double track/ fire road type stuff. Suspension forks generally preclude the use of a front rack, and generally complicate the maintenance of your bike. If you do decide to go with a fork, stay away from air sprung forks and opt for the coil&oil variety. They are less likely to fail in a manner that renders your bike useless or dangerous. The guys from Riding the Spine learned this the hard way, and it has proven to be the demise of a couple GDR racers. When an air fork fails, it usually sags all the way through its travel leaving you with a wacky a-c height and a silly HT angle.
I've raced and ridden rigid mountain bikes exclusively for the past 2 years with no problems. (including the leesburg baker's dozen!)

as far as clipless pedals go, i personally recommend them. but, if they are out of your budget its not the end of the world. i commute with toe clips everyday and am quite fond of them. it looks like of silly to spin around in cycling clothing with sneakers on, but you'll get over it. if you can work them into your budget, i would point you towards entry level time ATACs with a walkable SPD shoe.
sorry if any of that wasn't exactly clear, if you have any questions just PM or post.