I will not help you on the choice of which HD movies to choose (Troy, Black Rain, etc...)
That is 100% a personal choice, and is something YOU must decide.
But I will help with this question.
"I have the matrix trilogy on sd
is it worth it to double dip the matrix? (I just watched the sd versions, which is why i'm not that hot to buy them)"
The answer is a simple, YES.
Although, I am not fond of the 2 sequels...
I will tell you, I have all of them on SD. And the difference is night and day, the HD versions are a must have.
The Spiderman(s), I do not have on SB, only have the SD versions.
Will I be getting the trilogy on HD (BD), absolutely.