There is a field called "Location in Building" under "My Info" that you can use for this.
As for synching the two libraries, this is not easy. You can wait until October for Delicious Library 2, which will have sharing capabilities built in, or you can merge them by hand.
The easiest thing to do is just dump the guts of one XML file into the other and copy over the images, but that assumes you know your way around XML.
The second best thing is to export one library's contents and import it into the other. Unfortunately import and export are a bit out of sync these days so that also involves a bit of fudgery. The best, best way is to purge all but the Amazon number column and just do an import and reload.
You can always send your data files to me and I will merge them for you, but you probably want to have everything at both locations input first.