Hi
there's potentially loads of 'road hours' in each half of your two-week plan - so I am assuming that you are comfortable with that; it won't be relaxing (unless you nod off in the coach)!
With regard to your Wild Atlantic Way Drive, I would strongly recommend considering how much of it you really want to drive - each section (per the official itinerary. listed on the official website) represents about 8 to 10 hours driving time, non-stop (assuming an average 40mph - you won't do much better than that on the roads that form the route). You may find it far more enjoyable covering less total distance, but stopping more often.
You also don't state what month you are touring - if the summer months (say May through September) you will have 12 hours daylight (give or take); other months will be considerably less. If the point of the tour is to take in some of the West Coast's magnificent sites, then I'd suggest perhaps doing less of the route, and loitering longer.
With regard to Donegal specifically - you didn't state whether you are booking two nights in County Donegal, or Donegal town specifically. I ask this because Donegal (town) doesn't really need two nights' stay, unless you are going to use it as a base for day excursions (particularly to the Slieve League / Glencolumbkille area, in the west). However the first (or last!) entire section of the WAW covers all County Donegal coast and is in itself a 300mile + adventure drive; you could easily spend 2 nights covering the whole section. Much of the most beautiful scenery is in North Donegal, and Donegal town is in the south of the county - and it is a 1 to 2 hour drive to get across the county.
Lastly, the drive from Dublin to Donegal Town is about 4 hours, so ensure you factor that in..
Happy planning!