Yeah they could do tonnes of stuff with the Romulans, all those years between TOS & TNG and beyond, when they we're in isolation from the Federation, but must have been up to something, eg exploring the Beta Quadrant...
The Time Ship also has lots of promise, lots of crossover episodes and temporal shenanigans. How do they train people to cope with all the paradoxes without getting a hernia. And the EMH of the future would be really cool as well, could still be played by Picardo, could even be the same EMH as Voyager, depending how they end Voyager off... <breathe out>