One thing I wouldn't do is tie Insurrection in with the Dominion War, or any of the films in with the continuity of whatever TV series was running at the time (this has been suggested more than a few times over the years). The film has to stand on its own to appeal to a broader audience, not only at the time of release but also in its afterlife. The films are not slotted into the syndication reruns of any series. Insurrection could be played anywhere at any time. A 10 pm showing on HBO would reach more casual viewers who might stop at the movie and check it out. By tying the films into the TV series too closely, one takes a chance of losing that audience, who has to be brought up to speed. It would be like running a random episode without any of the others around it. If it is a standalone episode, no problem. If it's a vital cog in the ongoing arc, then it's not as effective.
Sure, a few lines of dialog could probably do it, but the farther away in time we get from a discontinued TV show, the less relevant it becomes. Tying the film directly to it would make it less important because it's slaved to another show rather than the series the film actually is a sequel of. If you're going to tie a TNG movie to any series, it should be TNG itself. But I always preferred the movies to work on their own, so one wouldn't need to follow the series to get it.