Want help deciding where to stop between Derry and Sligo

Trip Background:

Hi! I'll be doing a road trip through Ireland with my wife for our honeymoon in mid-late May. Our overall itinerary is Dublin -> Belfast -> Causeway Coast -> Derry -> Sligo -> Dublin. I've got pretty much everything planned except for what to do between Derry and Sligo. We'll be waking up in Derry, probably do a walk around the walls in the morning, then head out for the day. We've got a dinner reservation at Kilronan castle at 7 pm that evening (probably could push it later if need be) and would like to have at least an hour to get to our Airbnb near the castle and freshen up before dinner.

Background about us:

We love to hike and be in nature in general, but our hikes are usually strolls/wandering rather than climbing up a mountain. Not opposed to doing something a bit strenuous if the payoff is worth it. We're in our late 20s/early 30s and are physically fit. We love nature and chose to visit Ireland at this time of year specifically because its wildflower season. We typically prefer forest hikes over open spaces, but not a deal breaker. We also enjoy opportunities to learn, from the history of places to the geology and flora and fauna.

Potential stops on the day (probably pick 1-2 of these):

- Glenveagh National Park

- Greenan Mountain

- Cuilcagh (stairway to heaven)

- Slieve League

- Donegal Castle

- Benbulben forest walk

- Glencar waterfall

- Sligo Abbey

- Knockarea (and The Glen hike near there)

- Cliffs of Mahgo

Just seems like there's too many great options! Any opinions on the best way to spend our day would be greatly appreciated, thanks!