The most striking thing about some Star Trek franchises after TOS (especially TNG) is that while they TALK about the wonderful moneyless economy where many of society's ills have been resolved, the actual characters and plots are as full of overwrought sturm und drang as any soap opera.
The relationshiop between Chief O'Brien and Keiko is one of the most unpleasant to watch of any on all the ST series.
I'd like to see some of the "better world" that's supposed to exist in the ST universe but that we rarely see even a glimpse of.
It seems to me that TOS avoided much of the self-contradictory behavior evident in later series by dealing with situational morality plays involving other cultures. "We" could help them solve their problems without tarnishing our own image.
1) I'd really like to see some of the "better world" TNG universe - good, psychologically healthy people meeting challenges not of their own creation, along with with the optimism of TOS (Kirk never slunk away from encounters with more powerful aliens the way Picard did).
2) While "Enterprise" creates a whole new pre-TOS universe, I'd like to explore some of the referenced pre-TOS universe - long ship travel times, Captain Garth before his fall into insanity, the war with Romulus.
2b) I could easily cope with a fifth season of "Enterprise" if it included some of what I mentioned above - human relationships fulfilled, more direct pre-TOS connections.
3) I'd be happy to watch a "unified" Star Trek universe moving forward after the Voyager / DS9 era, and yes, again with the "solved problems in evidence" and "TOS optimism" I keep harping on.
At the end of the ST's television run I was left hungry for character development / fulfillment. How about Reg. Barkley settling down into a confident, successful officer (maybe with a wry, knowing wink for less confident junior officers) ?
Ro Laren is another character (who I believed to be dead, but apparently she appears briefly at the beginning of Nemesis?) who I'd like to see fulfilled. Absolutely one of my all-time favorite characters (until she "went bad").
It would even be good to see young actors from DS9, TNG and Voyager reprise their roles as captains, admirals and other successful, consummated life stories (none in particular).
I would watch another ST series regularly, unless it devolved into a Battlestar Galactica-like melee of conflicted psychotic losers.