Gosh, that really depends on what your interests are and where you've already been.... and how bothered you are about risk (still kicking myself I've missed going to Syria, Libya, Iran and Chad which all look dodgy for the foreseeable future). We went to MCT very much as an add-on to DXB and did have a long think first. I wouldn't go to Oman in preference for example to Egypt (but maybe off limits now?), Jordan, Israel, Turkey or even Tunisia. But there's so much to see in these other places that sometimes I find going to a mellow place without a lot to do forces me not to worry about ticking off all the major sites/sights....YMMV.