Hi there!
Oman has loads of things to do! If you're staying for just a week, I'd recommend two days in Muscat.
Nizwa is a little gem and in a ray of 60km there's a lot to see, including Al Hoota Caves, many towns with impressive fortresses, Jebel Shams, which is the country's tallest mountain and the Canyon.
South of Muscat you should visit the Wadis, the sleepy town of Sur and the impressive Wahiba Sands. Salalah, is in the extreme south of the country, about 12 hours non-stop drive from Muscat, but the best months to visit the city is between July and September.
You may want to check out some posts about Oman on my blog www.travelwithpedro.com</a>