In short, we can't answer these two questions, as the answers are 100% subjective. We can give you info about our experience using large format lenses, however.
A 90mm is very wide to me. For me, it is too wide for distant subjects, but useful for close subjects. It has a horizontal angle of view in between a 24mm and a 28mm lens on 35mm film, yet like all 4x5 lenses on 4x5 (or 8x10, or 6x7, etc.) format when compared to 35mm lenses, it has a larger vertical AOV (that of a lens about 22mm on small format), so seems even wider than 24mm.
The 120mm length (mine is actually 121mm) is wonderful for me. It has about the horizontal AOV of a 35mm lens on small format, and about the vertical AOV of a 28mm lens on small format. A great combination of my two favorite wides for small format.
If you need a lot of raw horizontal AOV for what you do, go for the 90. If you want a generally wide lens for landscapes, I would go for something that is not quite so wide, in the 105 - 135mm range.
This is what I am using to compare AOVs: http://www.mat.uc.pt/~rps/photos/angles.html. Choose your format and type in your lenses. It has been very slow lately, but it does work eventually, so have patience.