I will add to this as I do more research for next year's big trip...

Conservative Behavior


While in public view, Arabs behave conservatively and expect others to follow their example. Public Display of Affection is non-existant, as are arguments between spouses and friends. Joking and laughing are kept low also, which is not the case in private gatherings.

Privacy


Privacy is a cornerstone of the Islamic lifestyle. Houses are soundproof and all windows are covered. If one is visiting, it is expected that the person waiting to get in blocks any view inside of the house while the door is open. The word for "come in" is "Tafaddal," and is always accompanied with a raised right palm.

The save face concept


Arabs, by nature, are very non-confrontational. If a confrontation does come up, the wisest and most respected way to end it is to present a way out. The idea is to make it appear to bystanders as if there is no winner or loser - the examplary phrase is "Let me go think about it."

Admiration


When one explicitly admires a possession of an Arabian host, he might feel obligated to offer it, even if it is of personal value. Admiring something should not be prolonged for this reason. When Arabs receive gifts, it is a custom not to open it in front of the giver. The same is expected when they give someone else a gift.

Clothing


Men wear a one-piece covering referred to as a "Dishdashah" or "Thoub." The loose fitting garment allows for air to circulate and is white to reflect the sun. It is accompanied by a three-piece headcovering that is worn for both modesty and to block the sun. The bottom-most part is a cap, "Tagiyah," used to keep the hair in place. The Tagiyah is topped by a "Gutrah" or "Shumag," a shawl-like cloth designed to block the sun. It, in turn, is held in place by a black band referred to as "Ogal."
When in the house of a close friend, it is not required to wear the headpiece, generally wearing it inside is a show of formality.

Women generally dress even more conservatively, taking care to cover arms and legs, sometimes using an all-body garment called an "Abayah." It is best to follow the local examples concering face and hair coverings, in some parts of the UAE it is holy law to do so.

Dinner and Social Occasion

After a restaurant dinner, it is deep-seated custom that the host pays for it; it is critical to keep in mind that alcohol and pork go agaist holy law, it's respectful to avoid both in a Muslim's presence.
When eating dinner at a Muslim's house, it is customary to serve more than the guest can eat as a sign of wanting to provide for him. If you eat everything, you'll just be given more. You might notice that your host is pretending to eat, this is a sign that he is done but does not want you to feel like you are forced to stop. It is also customary for the guest to begin eating before the host.
When invited to a Muslim's house for a gathering, one will be received in the "Dewaniah," or gathering place. Most Dawaniah are for male guests only, females are usually received inside the house or in a seperate reception room. Occasionally, women will have a seperate gathering entrance from the men's. In conservative households it is considered improper to host men and women who are neither blood-relatives or married in the same room. Gatherings are held either daily or weekly and are open to family, friends and invited guests.
Guests are not expected to bring food or presents, but should take notice of the floor - often it is proper to take one's shoes off. Upon entering, the guest says "Alsalamo-Alikom," peace be with you, which is replied to with "Wa'alikom Alsalam." Once inside, the other guests will arise to shake hands. This takes place from the right to left, or with the person approaching you. If you are elderly or a first-time visitor, the host may offer you a seat at the head of the table. If coffee is served, the server will keep refilling your cup until you shake your empty cup and say "Bass, Shokrann." It is custom to always use your right hand and accept at least one cup of coffee.

Odds and ends


Showing the soles of one's feet to someone is deemed offensive, as is "thumbs up" and pointing at a person.