If a suicide story would have worked in Voyager, it would have had to be after a longer period of time, and after some traumatic event. Like, if they had done the 'Year Of Hell' as a full year arc like they wanted, it would have worked. Or maybe one of the Delaney sisters dies and the other attempts suicide.
The problem with having a mirror universe arc is that it was airing at the same time as the series that did a mirror universe ep every year. Though maybe last season it would have been better than the other retrospect episodes like Shattered.
And I think Course Oblivion is one of the best episodes in the series, though it would have been awesome if they'd had them getting home instead.
I love the 'Universal translator breaks' idea. And I like the idea of running into another Federation of Planets. Maybe they refuse to help Voyager because they don't want to interfere in Voyager's natural development.
What I would have loved to see was one where Voyager got really low on resources. Like, the replicator is broken, the holodeck is nonfunctional, the crew is deprived of basic creature comforts for several episodes in a row. Quark's theory on humanity being put into practice with Voyager, to see if they can still hold onto their Federation morality when their bellies aren't full and sonic showers aren't working.