I've been several times. We go to scuba dive, but also see the sights.
There's a hop on hop off island tour bus to see the main places of interest - Citadel in Victoria, Inland sea and what was the Azure window (the big arch in all the pictures that fell down a couple of years ago), Some ruins, various little cove beaches like Xlendi.
The main big beach is at Ramla Bay, there's a small beach in Marsalforn, which is where we stay, and there's a couple of other little shingle/cove beaches. Marsalforn has lots of Italian restaurants serving excellent pizza.
Day trip to Comino and the Blue Lagoon is a must.
You can walk all around the coastal path, but it will be too hot to do that in August. Which is why we usually go in May/June or September/October and spend a lot of our time underwater 
Bit of a trek from Gozo, but I'd see about spending a day in Valetta on the way there or back to the airport.