Good alternative to wood fascia trim
Assuming that you have one-by (3/4" nominal) fascia, I'd install steel wraps. They're commonly used in my area's harsh climate for an attractive, maintenance-free finish. Two sizes are available (for 6" and 8" fascias), but you could trim the top edge as needed for non-standard heights. The only preparation you'd need to do with your existing fascia would be to flatten out any warpage and replace any rotten areas with raw pine lumber.



Be aware that this product is installed by sliding it under a metal roof edge, and that it's nailed upward from the bottom along the narrow edge. Nailing the face (other than at joints, where needed) results in dimples that stand out in certain lighting conditions. Lap pieces such that the lap is less visible from entryways, etc., and so that water flows properly on rakes.