Not a big deal anymore. You probably need a business visa, which is a bit of a hassle but doable. Yes, definitely dress conservatively. I would suggest picking up an Abaya. They are light, floaty, and by far the most comfortable, practical thing in the immense heat. Don't need to be black. You will also have the assurance that you are in line with norms. It's not required to wear a head scarf, but bring one with you (you can normally purchase a matching one with your Abaya). You can have it falling lose when in most offices, but can raise it to cover your head, to avoid attention in the street (and protect from the sun). Don't initiate physical contact with men, but many Saudi men will proactively reach out their hand to shake your hand, to show they are westernised. So take any hand that's offered, but don't be offended if it is not. Think of it as a respect for your personal space.
This time of year, heat will be overwhelming, so would plan on taxis everywhere. If you are traveling at a good standard, you can expect excellent air conditioning of course. And food is very high standard. The Saudi coffee is subtle, mild, often with cardamon overtones - try it! Alcohol is illegal of course - including on flight in Saudi airspace. Don't take risks with anything at all in your cases that could be objectionable. There are tons of things to object about of course on a political/feminist level.... But the actual experience of traveling as an international business woman is generally very comfortable, and you will feel respected and might even enjoy the time off from your body being checked out/ being hassled/ hit on etc. Try to avoid making too many assumptions in advance. Eg I went to present to the top 100 of a Saudi company, and more than half were women, and they were vocal - better than we do in the UK!
Often executives are aware of Saudi's reputation and keen to represent their country positively. Public dignity is very important, so I'd strongly suggest avoiding political statements/ challenging local execs - they are no more (or even less) in control of what their government does than we are, and not free to express themselves anyway. Accept their hospitality and highly likely you will be treated extremely well.