I may have to do some business out there shortly - while I'm not a complete novice in the ME, having been to UAE before, I've not even been to Oman as a tourist. Reading up seems to suggest that a similar approach as I used in UAE would be sufficient - so conservative suits etc. However the UK guidance suggests only skirts for women which I'm a bit about since some of what I may have to do will involve working in the field.
Anyone any experience in Oman, and particularly if trouser suits are acceptable?
My experience of working in Oman is just two days' worth, but I didn't find it any different than being in UAE as far as dress code. Actually in Oman there were somewhat more local women around, working (for instance, as immigration agents at the airport). I wear a nice pair of trousers for most of my meetings when I travel, and that seemed to work fine there. I certainly didn't get any funny looks. I would not worry about it.
By the way, Oman is light years better than UAE as a tourist destination--I highly recommend spending the weekend out there if you can manage it. I did that, rented an SUV, and drove all over the northern part of the country outside Muscat. It was great! No one said boo as far as a woman driving, or driving around with just two other (Western) female companions. I've posted about the experience in some of the Oman/Muscat threads in the Middle East forum.
I haven't worked in Oman, but I spent two and half weeks there on holiday in 2005 and I loved it there.
My overall impression is that the local population is "conservative" but not "judgmental" and that people are "quietly friendly". I saw local women working in loose-fitting covered up clothing - often traditional (with headscarves) unless they were wearing uniforms. I didn't see any men in a business environment but other local men I saw were dressed traditionally.
We were in Muscat, a resort (Al Sawadi), in the interior (Nizwa) and Sur.
I felt comfortable as a tourist in cropped, but not slim-fitting pants, untucked button front 3/4 sleeve shirts (not fitted but not baggy) for day-to-day activities and sandals. I felt comfortable in tshirts and sleeveless long sundresses in some places but sometimes felt like wasn't being respectful enough - throwing a pashmina over my shoulders when walking to the restaurant or in the local convenience store did the trick. I didn't feel like someone was judging me; it was more that I felt as if I was making some people feel uncomfortable.
Oman felt like the safest place I've ever been in my life (and I grew up in a small town). We actually picked up hitchhikers a few time (e.g. people on a local road hitching out to the highway to catch the bus - one time we gave a 20-something man a ride from a village to Oman - he was on his way to start a new job at an accounting firm). We had some interesting encounters with locals. For example, 3 young women (high school students) approached us with a videocamera in the souk in Muscat and asked to interview us for a high school project on tourism.
So, the bottom line is that I think pantsuits are appropriate (and possibly more appropriate than knee-length or mid-calf skirt suits). However, I would avoid form-fitting trouser suits if possible (e.g. a jacket that ends at high hip over low-rise fitted/flared pants).