Well, one thing I think most (if not all) of our characters have in common is a lack of parents. So, perhaps that makes their end goal different. After all, Littlefoot and the Gang went to the Valley in the first place to meet up with their families again. With no families to turn to, our motivations would be different. I would imagine that, as more and more herds press inland, feeding grounds would become scarcer, and largely controlled by "strong" herds. Bearing this in mind, the concentration of Sharpteeth in these areas would be downright terrifying, reason enough for a group of young dinosaurs to make like a tree and leave.
So if we roll with this, now we have a reason for leaving, but we also have fugitives without a cause. How do we solve this? One of two ways. We could drop hints about a promised land, a la Great Valley, or we could focus this story around the journey, rather than the destination. Think of it this way- what's the most important thing these dinosaurs need now more than ever? Family. At the end of the day, I think they'd rather have someone to regard as family than a veritable paradise. With that in mind, I propose that our "journey" here is a mental one rather than a physical one with a set destination in mind. Basically, this means they can settle in whatever feeding ground seems best (this makes the northern journey idea work, as no adult coastal dinosaur in its right mind would actually want to go where it's cold). It doesn't have to be a paradise, it doesn't have to be a legend, it only has to provide refuge for a gaggle of kids who eventually come to organize their own "family" among themselves. Personally I envisioned a setting similar to Yellowstone, but that's certainly not a requirement. We're all flexible.
Bearing that in mind, I'll summarize the advantages taking a journey narrative over a destination narrative would provide:
-It's better suited for an RP. Story is told in small chunks rather than a large, overarching plotline, so it's more similar in style to a TV series than a movie, as an example.
-Our destination can be anywhere, as long as the characters find it comfortable to settle down. There's even room to adopt a "destination" narrative later on if the characters pick up hints of something legendary (like the Great Valley) down the road.
-There's incredible room for character development and subplots. There's nothing crazy going on here, no large, herd-threatening catastrophes, just kids trying to survive the odds. We have a chance to tell a very personal tale here, and I think it gives us the chance to provide significantly more depth than most RPs provide.
Anyway, just my two cents!