Sardinia route suggestions

Hi all,

I am off to Sardinia for a week in early June with the family and a few friends and have negotiated a day off to go riding with my mate who I am happily well matched to ability wise. I am staying up in the apparently swanky north east part of the island and have found a rental place that has a nice range of Canyons for hire, which is here:

https://www.google.co.uk/maps/place/Sardinia+Cycling+Costa+Smeralda+Bike...@41.0906596,9.4354596,13.75z/data=!4m5!3m4!1s0x0:0x9c7fb4dd078fef73!8m2!3d41.095026!4d9.451437

Neither of us has done much riding this year and certainly not much in the way of  distance so we are looking do do probably about 80-100km bearing in mind that it is probably going to be boiling hot. Currently thinking I have two options - one would be a possible killer day of riding from the rental place to Mount Limbara to take on a big climb. Doing a route on Strava suggests that it is basically going to be 60km with 2500m of climbing on the way out, and then straight back the same route but all the way down hill to return. Apart from the view from the top, if we can get there, not sure if this would be the best showcase of Sardinia or not. Plus it looks like a really brutal first few hours if it is pushing 30 degrees.

Other option would be to do a coastal route from the rental place and get good views of the sea - guessing this might be pretty up and down which is fine, but also could be a bit mental for traffic?

Anyone got any exerience suggestions? Slight possibility we can sling the bikes in the back of the hire car.