Sorry if I'm dense, but I am totally confused about Surcharges/Taxes of BA vs. AA (or CX for that matter). I have searched and read many posts. I need to book my 5th DONE4 (have been ending one and starting another in CAI each year). If I am correct:

1) AA is applying fuel surcharges now, although the add-ons are probably somewhat less than BA (maybe $500 less);
2) When I finish my current DONE4 in CAI in May, I can fly to IST for $400 in J on Turkish. The IST RTW is about $1,000 cheaper than ex-CAI, but is the difference in surcharges & taxes going to eat up any savings? i.e., I can only ticket BA or CX in IST, not AA, per posts;

This is of some practical interest to me. I am a bit tired of CAI, having been there 4 times in the past 3 years... IST might be a welcome change. But, when I end new DONE4 in IST in 2007 to begin a new RTW, will airlines have adjusted the fares so that ex-IST price is significantly higher?

High class problems, right? (Whether to fly business class from Turkey or Egypt). But still interesting. Maybe I'll even test the waters, and set up DONE4 ex-CAI with AA, and one ex-IST with BA/CX and see what the final cost would be.... Also transiting CMB in May, 2006, so have contemplated issuing ticket there and just dropping the last segments on my current DONE4.

Feedback appreciated.