If you're writing a fanfic, I'd say that Ashley Valley is a good place to imagine where the fictional Great Valley might have existed. But I also agree with the other comment someone posted - millions of years ago the arrangement of the earth was quite different (Pangaea), so, if hypothetically the Great Valley had indeed been a real place, for all we know it might have split up like pieces to a puzzle.
Thank you for sharing the photos, by the way - it's intriguing to see the semblance between the Great Valley and Ashley Valley. =) I had actually never heard of Ashley Valley before this, but its' likeness to the Great Valley is interesting!

I have to admit, I thought more-or-less the same thing.
The ending did seem slightly out-of-place when we saw everything that Po went through to come to terms with what happened to him in his past, and not to mention the seemingly newly-forged relationship, the father/son bond between him and Mr. Ping.
I honestly can't see how they would continue with that in later movies...it would be weird if Po's biological father met Mr. Ping...

Lol, it would be interesting to see Cera fall for someone. I agree with LBTFan13, I can't see her falling or becoming infatuated with someone easily. And well said, that even if she did, it would most likely strike up competition. ^^ I'm thinking of an episode from 'Rugrats' (a show I really don't like, but had seen this instance) in which Angelica falls for a tough-guy kid like her, but instead of acting like she was smitten (which she was), she was competitive with him and tried to prove she was better, or tougher. I can see Cera doing something like that with a boy three-horn. Would actually be pretty cute if they did it right.

I always felt more bad for Ducky when Mrs. Maia (or whatever that dinosaurs name was) tossed her away. Not when she got stung by bees.

Also meant to add, thank you for the welcomes everyone, it's greatly appreciated! ^_^

This might be an insignificant point, but you could also take into consideration that (at least as far as I know) no one really knows how young dinosaurs age. =)
In the first post it was mentioned that Cera looked bigger next to her dad at the end of the movie, so she might have grown since then. Maybe it's safe to assume that different species of dinosaur age at different rates, just like today's animals do.
If Ducky didn't look different in size from her siblings, maybe they just age differently? There's a lot to speculate. =)

That certainly is an intriguing thought. I had wondered before, as well, exactly how much time it took Littlefoot and his friends to get to the Great Valley - and not to mention what other obstacles they must have faced during their journey.
I've always sort of looked at it from a "cut-and-paste" perspective, I guess you could say. That anything and everything we didn't see in the film is, maybe purposefully, left to our imagination and that it's up to the viewers to fill in the blanks. In my opinion, it really could be taken many different ways...
For instance, as far as behind-the-scenes scenarios that might have happened to Littlefoot and his friends: how would Don Bluth have created the additional parts of the story? How would fans/viewers have created it in their minds? Or how would todays' filmmakers tell that untold part of the story?
There's so much to consider, which makes it such a compelling topic.
I'm going to have to share the others' opinions though, in that it really would be a "double-edged" sword to actually try and create a prequel/midquel. I doubt it would ever be done, but it still would be interesting if was carried out. Technically, it really could be done - not just done, but done well - it's just sadly unlikely because of the way that people tend to make prequels/sequels. I imagine, that if a Land Before Time movie was made that told about the other dangers they faced while traveling to the Great Valley, it might end up being a watered-down version of the other sequels and wouldn't have the same feeling that the first movie had.
If anything, one interesting way to get a look into the unseen dangers - at least, a version of them - would be if someone would write a good, believable story about Littlefoot and his friends' adventures in the Mysterious Beyond.
In fact maybe there already exists such a story; I don't know. (It's been a while since I last browsed the LBT section of FanFiction.net, which seems to be where most LBT fanfiction is found.)