Okay, I figure it's time for me to chime in here too.
I've given this some thought and rounded it out to a few basic elements I'd like to see. I suspect some of this may be somewhat...against the grain, so to speak, but here we go!
1. Godzilla MUST be treated like a character, NOT a plot device.
This seems like a no-brainer, I know, but bear with me here. What's the most common interpretation of Godzilla? "He's a force of nature." The basic idea Toho has almost always gone with is that Goji is a walking natural disaster: uncontainable, unstoppable, and basically impossible to understand. While this has worked well in the past, let's face it: more often than not, this reduces Godzilla and co. to walking plot devices rather than actual characters, excuses to have cool action sequences and little else. IMO, this will not work as well with an American audience as it does with a Japanese audience.
If I were to describe Godzilla as a character, I'd describe him as flat and static. That's not a bad thing, mind you - there are plenty of flat/static characters that have been successful in Western cinema: James Bond, Sherlock Holmes, and the various Slasher villains are all great examples. However, even though these characters are mostly static, they make up for it by trying to round them out: Sherlock Holmes and James Bond are (after a bazillion films each) well developed characters, and even the Slashers generally are given motivation/backstory, if not actual development, for what they're doing.
Godzilla is rarely given either motivation or character development.
Let's take a second and look at the most successful Western giant monster: King Kong. What made that character so successful? Well, in part, it's because he's always been treated like a character: he has motivation, he has character development, and he has an actual character arc: Kong falls in love with Ann, and that love destroys him. It's basic, but it works. What is Godzilla's character arc? In the mind of the average American moviegoer, it's either "Godzilla shows up, destroys city, then dies/leaves", or "Monster shows up, Godzilla shows up to fight it, then leaves." Not exactly the most compelling story ever told. ^_^()
I may be beating this to a pulp, but I really just want to emphasize that I want Godzilla to be more than a walking plot device the characters must respond to (as Zilla was in the '98 film), and the best way to do that is for the writers to find an appropriate motivation and devise some sort of character arc with even a meager bit of character development. Even James Bond changes in some
way by the end of each installment, especially in the newest films, so I think it's fair to let Godzilla be granted some development too.
2. Godzilla should look and act like Godzilla, but the filmmakers shouldn't be afraid to take some liberties.
By this I mean what we all expect and is probably obvious: Godzilla will be made to look more "realistic". For better or worse, it's likely to happen - and, really, I don't mind so long as the result still LOOKS like the character I know and love. I've seen plenty of fan redesigns that try to incorporate more modern dinosaurian features that don't end up a butchered job like Zilla turned out (hell, we've all see the FAR superior unused concept art for that film). Atop of that, Godzilla probably won't be lumbering: he's a dinosaur, American audiences expect some agility. This is likely to be the most energetic Godzilla we've seen since the '70s. Which, again, I'm fine with (for better or worse) so long as the result remains an unstoppable wall of destruction and radioactive fury.
However, there's one thing I don't think anyone has discussed or considered which SHOULD be: Godzilla's size.
I think we've all sort of assumed that Godzilla will be, without question, at least 50m tall. Why? While the destruction he can wreak is awesome, I've always thought the smaller monsters provided some of the more interesting scenarios and stories. What if, rather than 50m, he was as short as 35m (Kong in KKE)? Or even shorter than that, maybe as short as 10m?
I'm sure someone will scream "BLASPHEMY!", but IMO what we lose in property destruction we'll gain in some really kickass and intimate action sequences. Can you imagine how awesome it would be for a 10m (about Megatron's size in Transformers) Godzilla to shrug off a barrage of tank fire, then leap atop a tank and, partly riding it as it tries to escape, tear off the turret with his jaws so he can blast the inside with his atomic fire? I certainly can!
So, yeah, let me be the first (I think) to advocate for a dramatically shorter Godzilla. It'll be awesome in the end, I promise! ^_^
3. Godzilla has to fight somebody.
Really, this was the biggest mistake of they made with the Tristar film. Yes, Godzilla can work well solo (especially if he's made shorter and more energetic, but even traditional Goji is fine alone), but why would you let him be alone? Unless we're doing a straight remake of the original, there really isn't much point IMO to doing a solo film: American audiences expect
Godzilla to fight somebody. Why deny them that? And let's face it: a grand finale fight between Godzilla and another kaiju will spice things up, draw in bigger audiences, and with the budget they're liable to throw at this could produce something truly spectacular. IMO, it doesn't matter who Godzilla fights, but a fight HAS to be in there somewhere.
(Though, if we get a miracle and this is successful enough to have a sequel, I vote for Goji to get a rematch against Kong in Part 2!)
Anyways, that's my 2 cents on the matter.