Why do I have a problem with this episode?
Because it isn't connected in anyway to the arc Enterprise had at the time. "Terra Prime" is one of my favorite ENT episodes, and quite honestly would be a better finale, in my opinion. The fact that the death of Trip and T'Pol's child or the human racism that occurred does not even factor in to the finale. Um, that was some pretty important character stuff there. Do you mind not leaving it out of the picture, please?
Secondly, how they killed off Trip is a big mistake. Some may complain about revealing that a character is going to die somehow cheapens the death, and I will agree that is a tight rope to walk. However, the fact that the finale involves a main character getting killed by criminals because he ran in to a situation that should have been handled by security or even the MACOs, which Riker dresses as in the episode.
Finally, as many have mentioned, it forces TNG in there for no reason. Ok, a small reason, to acknowledge Trek's TV history. The problem, as has been hashed out, is that the Pegasus episode handled the Riker dilemma with more decorum than TATV did because it could focus on Riker's relationship with Picard. Here, Riker apparently needs his hand held to be convinced to tell the truth. Again, it's another character inconsistency.
As for ideas to make it better. SF Debris, in his review of this episode, made it very simple. ADMIRAL Riker is preparing a speech to induct the 200th member in to the Federation and is looking through historical records for inspiration. He doesn't participate, because his presence reminds us that this is on the holodeck. The episode plays out even as Riker observes and thinks, but he isn't the major mover here.
I would build off of the idea of human racism, with the criminals being mercenaries hired by someone to try and destroy the conference. Enterprise, being in orbit for Archer's speech, try to stop them. Trip and T'Pol resolve their feelings with each other, and Archer works to save the coalition, even as he prepares his speech.
Finally, if you kill Trip, or anyone, it really should count for something.
Finally, and this is based on SF Debris idea, is to have the one instance that Riker has to interact with the crew, be a brief moment, where one of the ENT crew, probably Archer, get a one on one interaction, that give Riker his inspiration.
And, you fade out from Archer's speech, not "Computer, end program."