I've seen both Switzerland and Middle East (read: UAE - Dubai) being quite popular, both for reasons of "more $ at the end of the month" with a high/higher living standard
Very different locations though:
- Switzerland is often found to be very suitable for families with children but relatively dull for others. Be careful though if you would require international schooling for the kids, this costs you an arm and a leg if your employer doesn't provide this as an expat/relocation package
- Dubai is more of an artificial place to stay so quite the opposite. Some consulting ex-colleagues love it and have been there for several years now; others found it great for a couple of years but not for the longer run
No clue about Singapore, only know a few non-consulting folks there so their mileage may vary very much.