I would have gone with Graham Greene (Dances With Wolves) as Chakotay. Older, wiser, a real sense of gravitas. Would have set up a more interesting relationship between that chartacter and Janeway, IMO.
That's a pretty good suggestion. Beltran had some very lousy performances but occasionally some good ones. Definitely not what I'd call a seasoned actor, but certainly better than Blalock. She had only a handful of engaging moments in the series. Most of the time she was so stiff. I don't think she really got the gist of how to behave like a Vulcan. Mark Lenard was superb, perhaps even better than Nimoy. You could definitely see personality behind the wall of emotional control.
I'd say Crosby was the worst and I agree with what someone else said--it was good she ejected herself from the series when she did. How her career turned out afterward certainly tells a lot.