Interesting, but simple and try lot's of new airlines. Hmmmm.
Depends what you are "in to", but for interesting I'd suggest maybe using OS from IST through VIE to Kathmandu. (An alternate would be to try out one of the new kids, JP, from IST via Ljubljana to VIE to KTM.)
IST-DXB-SIN with SQ is too straight forward.
From KTM you can get to BKK on TG and then continue with TG to Brunei - another off the beaten path destination. From there SQ can get you back via SIN to MEL. Or, to maximise miles, try SQ to PER then NZ to AKL and back to MEL.
Another miles maximiser could be using TG back to BKK then SK from BKK to SIN to link up with SQ - get another airline into the mix that way.
You've tried AC Exec 1st, so if you don't want any of the South Pac islands between Oz and U.S. (all accessible via NZ) then try out UA's International Biz product with MEL/SYD to SFO/LAX.
Or do a SYD-ICN with OZ, down into Japan with NH and across the Pacific to LAX with RG if you want to add another 3 carriers to your experience.
From there not much choice of carriers for the internal NthAm portions, but I am led to believe US's A330 TransAt service is very good in C which is something to keep in mind.
LOT can get you from WAW to IST if you want to add them into the mix to try them out and BD and LH can be used for other intra-Euro segments as well as SK if you haven't used them on BKK-SIN.
You could feasibly get almost every :-: carrier into the trip if that's a definition of "interesting" !! My two bobs worth anyway.