Just gotta work out the best way to populate the tag now!
Since you have a lot of the information in your tags already, you can probably use the Additional tagging & reporting tools plugin to quickly transfer it to the custom tag. Just be sure to test, test, test on a few files until you're sure that it's working as desired.
http://musicbee.wikia.com/wiki/Additional_Tagging_and_Reporting_Tools
I've been looking at that but can't work out a way to do it. I currently have the location as part of the band name and I can't see any (obvious) way to parse the tag and extract parts of it.
Anyone know if you can sort by the end of a column value? I don't mean Z-A instead of A-Z. I mean the column is actually sorted by the last chars of the string. That way you would get all xxx (London, England) and yyy (Chicago, IL) tagged bands next to each other. Even sorting by say the last 10 chars would probably work. I can then multi-select and tag manually (better than nothing). I can't see anything in the custom sort options to allow this. Can't believe it isn't possible though!
BTW this whole 'location thing' can get pretty complicated. There's quite a few scenarios when you start thinking about it. Mainly with big cities and the UK. The UK is England, Wales, Scotland & Northern Ireland. Within those countries you have counties (ie Hampshire, Dorset, Cornwall etc).
ie
The Ramones (Queens, New York, NY, USA)
The Business (Lewisham, London, England, UK)
Strate Jacket (Shirley, Southampton, Hampshire, England, UK)
Probably easier just to ditch the UK all together. Stick with the countries within it. So go with
<suburb><city><state/county><country><continent>
(may as well add continent in there - today I want to easily hear all my music by bands based in South America...)
Also I'm edging towards multiple custom fields. Will make it easier in the long run I think. Plus not sure you can do $First(<customtag>) in Theater Mode so if you display location it doesn't look that good with all the semi colons in there.
Anyway - thanks for the pointers. I'm getting there...