If it were my team I would roll Miller + Reimer, but I'll make it clear that I typically don't hide goalies if i still have a category to win (in this case shutouts). It's a tough call because a lot of teams are going to take the foot off the pedal to rest for the playoffs but I still like Miller's chances against Columbus.
As for which starts to be worried about on his side, I would really be worried about his Lehtonen start against Minnesota because that is a crucial game for the Stars playoff hopes...they're going to leave it all on the ice. I like their odds against Minnesota who hasn't been the biggest offensive powerhouse lately.
Like I said, this is just what I would do if it were my team. Good luck either way.