Personally having had the conversion van and now an SUV, I would take a properly equipped conv van. More room, like you said, which is more comfortable. A pick up truck with 3 kids will not make for a fun trip! Heck a 2 hour trip will be hard let alone a 2 week trip!
Another option, which is what I should've done from the beginning was to get a large class C or a class A MH! Then all you need is a towable SUV/minivan.
Wife Kim
Son Brandon 17yrs
Daughter Marissa 16yrs
Dog Bailey
12 Forest River Georgetown 350TS Hellwig sway bars, BlueOx TrueCenter stabilizer
13 Ford Explorer Roadmaster Stowmaster 5000, VIP Tow>
A bad day camping is
better than a good day at work!