The question is right there.
I'd like to see the Joes Beachhead,

(or his niece), Flint, Lady Jaye, Jinx (just because of the gal who seemed to be her in ROC) and a cameo of an old Tunnel Rat (only to see Larry Hama as the character), not all in the first sequel, but in the film saga.
To make space for them,

, Heavy Duty and

should slowly get away from the spotlight (nothing against them, but too many people would be bad to the saga), while

is put in a non-battlefield duty.
For

, it would be good to see

in the first sequel; he is already coming late by not appearing in ROC. He could release

,

and

.
It would also be good to see

or

(I mean Wild Weasel), depending if the main vehicle battles will be at sea or air (if they happen on land, an air-to-land aircraft piloted by

would still be a good idea).

must return and reveal he DIDN'T kill Hard Master, and the real killer should be

.
The Dreadnoks should appear led by Zarana, keeping her as

's sister but staying with the idea of

NOT being a biker, so his sister's lifestyle would cause a rift between the siblings.
And Slice for the 3rd film. He's awesome (not as awesome as

, but still awesome).