gtaflyer,
The allowances that I can immediately think of are:
Wife Allowance (no girlfriends, no mistresses)
Child Allowance (up to four dependent children younger than 19)
Educational Allowance (depending on if Primary or Secondary level and if depending if being sent to a local or boarding school)-- probably will not cover costs in their entirety, depending on which school you choose.
Accommodation Allowance (if not taking company housing)-- you will probably have to supplement some money depending on your personal standards.
Transport Allowance (pays about a 1/4 of the two-year load I have on a new economy car)
Communication Allowance (a stipend towards your phone bill)
ATP Licence Allowance(they give you a few dinars a month if you have the ATP)
I will not mention the amounts since it would be pointless as it needs to be balanced in terms of the local economy. Costs of living are less though than in Dubai and Qatar.
Likewise, as far as the Bond goes, I can tell you that it is a three year, pro-rated bond with two different amounts depending on the type of aircraft you are training on (the A-320 bond is slightly higher amount than the B-767). It accrues in cost until you finish your training, and reduces in amount for every month you are working with the company after finishing your line indoc. After 36 months, it is at 0. Off all the monetary issues that are important, I worried least about the Bond because if you are planning a career with GF, it is rather irrelevant.
Echoing jackbauer's comments, Bahrain is definately one of the more livable places to be in the Middle East. What he has not mentioned, and still remains to be seen, is that there is no shortage of rumors on that a Muscat, Oman base will be opening. One could easily argue that Muscat is an even more attractive place to live than Bahrain-- many experienced Middle Eastern expats rate Oman hands-down the best place to live in the region-- more laid back than Bahrain and especially Dubai, offering a nice atmosphere for the lifestyle conscious-- especially outdoors or water-sports lovers. If it does happen, Gulf Air will, IMHO, have bases in two of the most liveable cities in the Middle East.
A friend of mine observed that after 3-5 years (if not earlier) many expats do suffer from homesickness. Regardless of how liveable a foreign country may be, it will still be a very different environment and what you get out of it is directly proportional to what you put into it. I've observed that Gulf Air, like other companies hiring expats, do look for people with a multi-cultural/expat/multinational background as there is a greater chance that they can weather trying times. On the whole, I've found GCC locals to be extremely welcoming and accepting of expats.