Since I never answered the original question (well, I kind of did but in another thread entirely):
I like moving forward, and ideally I would want to set my own series soon after Hoban goes boom. On a ship "opening up" formerly forbidden space. The collapse of the Romulans holds all sorts of possibilities: Political Intrigue among the remnant fashions, subject species never before seen, old resentments kept down by Romulan power now bubbling to the surface (Like happened in Post-Tito Yugoslavia among other places), the reappearance of whatever other "matters of greater urgency" caused the Romulans to take their long sabbatical (that one Lost Era tale can't be the whole story, can it?), dark new powers on the rise on the other side of Romulan space...