I have had my Titan for about a month now and have gone on one 3 hour trip and a few 1.5 hour trips. My wife's '03 four-cylinder Accord was previously our long road trip machine before the Titan came along. Granted, these don't even come near to doing 8-hour trips as you stated you would be doing, but here are a couple of observations I've made that you may find relevant to your situation:
+ The Titan is much more comfortable on long trips, especially with family along. The ride is smoother and more spacious than my wife's Accord. For example, when we had 4 people on the 3 hour trip, everyone remarked that they felt much less fatigued upon arrival compared to when we made the same identical trip in the Honda.
+ I feel a heck of a lot safer driving my family around in the Titan than I would in my wife's Honda.
+ The extra cargo space factor is great in the Titan. I thought the bed divider was a waste of money at first, but I've used it virtually everytime I've had cargo in the bed. With the car, it was like doing a jigsaw puzzle each time we loaded up the people and the trunk. But now everything goes in the bed. When stuff can't go back there, the fold-up seats in my CC take care of all but the biggest stuff.
+ If you're concerned about MPG, then stick with your car. Getting any truck will not make much difference overall in gas mileage once you consider the very slight percentage loss in MPG compared to added versatility. For instance, the much smaller Ridgeline has a very small MPG advantage over the Titan. I happen to like the Ridgeline, and I love its AWD/4WD system--but it's overpriced by about $10K and offers less value to me compared to the Titan.
+ My wife is from Mexico and we are considering driving to central Mexico this Christmas for her family reunion with our Titan. That will be the mother of all road trips (36 hours driving time) and so far I've seen nothing that can stand in the Titan's way of making the trip safely, reliably, and comfortably.
So in a nutshell, I think the Titan is an excellent candidate for long road trips. It's extremely versatile, comfortable, fun-to-drive, and reliable (I have heard of very few breakdown issues with the Nissan Titan compared to other makes). At this point in time, our country's embarrassing dependence on oil (and, yes, I'm aware of my status as a V8 owner) is making driving a large vehicle less economical, I'm sure the Titan will be my road trip ride for many years to come. However, if you drive alone, don't need the capacity or versatility, or really need to squeeze as much as possible out of a gallon of gas, I'd say stick with your Honda.
Good luck,
Mark