We mostly use 1m ortho imagery but better in areas near airports.
Be careful if you plan on making scenery that is inside of or touching our imagery as it can cause graphical issues and holes within the terrain.
I'd primarily create scenery for myself so if I break something it's only affecting myself. If I think it's good enough to share I'd first ask some fellow forum members to beta test it. I'm still learning the ins and outs of scenery design, watching tutorials and reading through the threads here on the forum. It will probably take me a few months even for a small scenery area, as my second daughter was just born on Saturday and I'll be occupied with family life for quite a while.
BTW is there any information about the mesh / terrain height map resolution for Utah? In FSX the standard mesh resolution was 76 m but I guess Aerofly is way better than that.