These responses are wonderful...and cover pretty much my whole conundrum...I shouldn't have expected less!
I do know how to do fill-flash, though as 2F and a few have mentioned, when I have had the flash with me on trips, I have never used it. I am talking here of my latest flash which is a canon Speedlite 580EX. It's big and epensive and it seems crazy to drag it all the way across the world to either not get used or get stolen (GOD FORBID!)
I do have an old fixed head 220EZ, and the comments in this thread and some PM's have got me thinking small may well be ideal here. I am only looking for it in portrait situations, and so can leave out the bounce capability etc, and I can bring it out for specific occaisions, take little room, and not unnerve anyone with a huge appendage to the camera...going to test it out, since it has been 10 years since it was last used...fingers crossed..
By the way, my approach to fill varies. In general to create some background separation under-exposing the scene by about half a stop, and knocking about a stop off the flash compensation seems to work fine in relatively low contrast type light. For high backlight, I ironically find (at least with Canon) over exposing the flash by a stop seems to displace the shadows...anyway, long time since I did it...
Rgds, Kal