I presently have a Conley Ranger Series 2000, a Farmtek High Tunnel and an Atlas Greenhouse Systems single bay, Snow Arch Gutter Connect with 8' side walls. Of the 3 I like the Atlas Snow Arch the best. The high side walls allow better air circulation and an overall larger feel. You would have to check with them for snow load rating, mine is in Indiana and have had no snow load problems. They also offer the RT gutter connect which I believe is even stronger. I don't know what your requirements for hanging baskets are, but I'm planning to add a second bay this fall primarily for hanging baskets. Every time I've talked to the folks at Atlas I've had good service, and would fully recommend them. If you decide to go with Atlas, go with the metal frame end kits, they work real well and will make finishing the greenhouse so much easier.

I concur with plantman. Atlas is a very good company to work with. We have two snow arches and are quite happy with them.
It also depends on how many baskets you want to hang. You can easily get 250+ in a 30 x 96. Our next house will be the RT max Muscle.
Looks like your in Minnesota and my guess is they will recommend 4ft on center arches for a snow load of 30lbs per sq ft.

mylu, my neighbor has Rt's and I have snow arches.
don't let the marketing fool you.... snow arches can hang more weight.

at one point we had 2200-2400 10inch baskets hung in a 30by96