If I have to choose, I'd rather Carol Marcus come back for the next film.
That said, the more the merrier. Chapel (bring), Rand (it), Kyle (on), Leslie (all), Arex (the), M'Ress (way).
We need more female characters than just Uhura. I kinda would liked to have seen a Doctor Chapel (as she ocassionally became) or even Intern Chapel - a ship that big needs more than one Doctor - hey, how about Dr. M'Benga!? And a Young Rand (Perhaps as a Checkov love interest.) And definately an Arex and M'ress - as we saw a believable Arex-like character in Trek '09. (But I like more Cat-like M'Ress, not those *supposed" "Caitains" (twins) we saw in "Into Darkness"
(I'd also like to see he female Admrial or Fleet Capt. "Number One" - given a name now - taking Pike's place as Kirk's overseer.)
And a Kyle, Leslie - too! MAybe a young Decker and Ilyia too!
And these don't need to be full-fleged characters! In fact, better not they are - not mouch space for more. We can squeeze in Marcus, but that's about it.
No, they would be more like Keenser. Just so we have familiar crew in the background, rather than just having unknown random extra-of-the-sceen. (Thour I REALLY want to know more about who/whatever that seemingly cybernetic bridge officer is.
Also - I'd liek to see more background alien crew-members. Maybe even some VERY non-human ones. Like how about have something like a small dinosaur or octopus or even just some...I dunno...be creative! Somethign like looks like a Lovecraftian "Old One"(?). Just have them walk by in a corridor.
Some classic aliens like Tellerite and Andorian - Deltan, etc - crewmembers in the background too!?
How about a Xindi soimething-or-other!
Yeah I'd like to see more established characters in cameos and lots more crew from the 'core' Federation races of the TOS era instead of random visually striking ones. And of course, Andorians ARE visually striking.
Decker and Ilia would be about NuChekov's age so some cameos from them would be really cool but Rand was about a year older than Kirk (I believe they showed a screenshot in Flashback which used the actress's real age as a basis) so her birth would have pre-dated Nero's incursion and we already know from Charlie X that she doesn't like teenagers
I'm perfectly happy if they use actors for cameos and then re-cast if they decide to use the character more fully later.