Heya,
So, I just finished watching Giant... and I thought I'd post my initial impressions and then I'll leave this topic alone. Nothing I say here will constitute any kind of real spoiler.
First of all, Liz Taylor is just wonderful in it. I think she really carries the film. And she and Rock Hudson certainly are the dominant protagonists in the movie with James Dean's character hovering on the fringes/margins as an outsider (which is what his character is).
Overall Giant reminds me of BBM in that both look like westerns in every way (location, costume, certain plot elements) but, each really can be characterized as other genres as well. As we've been discussing there's a way in which BBM can be seen as a pure drama/love-story and, it's very evident that the best fit in terms of genre for Giant is really a classic melodrama (which is not at all surprising given Rock Hudson's involvement in the film).
One other big thing that they hold in common is that both are based on literature written by female authors (in Giant's case the novel by Edna Ferber). And, both films are/were socially controversial. I watched a bit of the special features on Giant and they begin by making a point about how difficult it was to get the film funded and made. It was apparently such an unpopular/controversial book in Texas that there was a lot of furor over it initially. Like BBM, Giant highlights big social issues (but in a somewhat more blatantly didactic way)... in the case of Giant the issues really are sexism and racism/poverty.
And then there are some fun details that could stand as comparisons with BBM. Right after the opening credits, the film begins with a train coming into the frame much like BBM. And, later Thanksgiving is a big highlighted/tension-filled holiday in Giant and compares two different Thanksgivings happening simultaneously in two different locations. When it comes to physical comparisons between James Dean's character and Ennis, well the comparisons are strikingly numerous (too many to elaborate in detail). In terms of mannerisms and certain poses there's most certainly something going on between those two characters. They're definitely not exact (not at all), but there's definitely a lot to compare... even things like a certain mumbled/taciturn style of speaking. Some of these comparisons come across better while watching the action of the film than in looking at these still photos.