Hello Brianne, it's great to see Ghyslaine's suggestions were helpful to you! I'm sure that, depending on the car and car rental
company you choose, you will find a great deal.
Your itinerary sounds wonderful, by the way! It gives you a great chance to compare two museums dedicated to the Titanic: the impressive Titanic Belfast, where the transatlantic was built, and the Titanic Experience in Cobh, which was the ship's last port of call. West Cork is a stunning area and you will definitely love sites like the Old Head of Kinsale, Sheep's Head (our narrowest peninsula!) or the Beara Peninsula - you could even take the only cablecar in Ireland and reach the unspoilt Dursey Island.
In Killarney you will find lots to do with many nice restaurants: it is the starting and ending point of the scenic Ring of Kerry as well as the gateway to the Killarney National Park, so rich in not only history (with Ross Castle and Muckross House) but also the loveliest fauna (red deer live there!). Galway is well-known for its colourful, lively atmosphere and this will be enhanced during those days thanks to the Galway International Arts Festival taking place from 11 to 24 July. Lastly, you'll love Donegal: it will feel like standing at the edge of the world, facing the Atlantic Ocean on its high Slieve League Cliffs and reaching Ireland's northernmost point, Malin Head. Returning back to your roots will be fun, being surrounded by so many exciting adventures! You're going to drive along the Wild Atlantic Way and, when heading from Donegal to Belfast, make sure you drive on the Causeway Coastal Route as the amount of legendary sites there will amaze you (my profile picture, Mussenden Temple, is proof of that)! On top of that, the city breaks at Belfast and Dublin will provide lots of musical and cultural experiences.
I've collected all this information in this online album
for you. If there's anything else we can help with, please do ask. :)