Having just done a trip to Utah after a 20 year break from western ski trips, I'm in a decent position to respond. Day 2 of the trip featured a demo day at Alta in fresh snow - 5" overnight plus another 4" during the day. And we found some runs where the snow was 12" plus deep. I demoed skis in the 95 mm range -- Stoeckli Stormrider 95 (great ski -- very smooth), Atomic Vantage 95 (very solid ski), and a lighter, more new-age construction Dynastar (which I hated). At the end of the day I also took my Kastle FX84s out for a few runs. For me, there wasn't much of a difference between the 84s and the 95s in the powder and cut up powder at Alta that day. Now, if I only skied 8" of powder and chopped up conditions, the 95s would have been a better choice, but most of my time is spent in non-powder conditions in Maine, where the 84s are a better choice.
Where I did see the limits of my 84s was the next day at Solitude, where it was 16" of fresh (and still snowing) when we arrived the next morning. In bottomless snow, something in the 105 - 115 range would be a significant advantage.
So if it were me for a 1SQ where your primary hill isn't the Rockies, I'd go for something in the 85-90 range for conditions up to a foot of snow (FX85 and Stormrider 88 are great choices albeit expensive), and then rent something in the 115 range for deep powder days.