Multiple output destinations means one standard workflow won't cut it. Lightrrom uses the ProPhoto colourspace internally, slightly wider than aRGB. If your output is going to be viewed on a standard monitor it needs to look good in sRGB - edit with your monitor set to that. Most outside printers also expect files to be in the sRGB colourspace. OTOH, if you have a good printer at home, it can usually reproduce more colours than sRGB, in fact, often more than aRGB - when getting a file ready to print, use aRGB or even the monitor's native wide gamut colourspace. The idea is that the colourspace you use for your editing display should mimic the colourspace of the final destination so that what you see on your screen as you work looks like what the viewer of the final image is going to see. Thast presumes you're viewing RAW images, if you have JPGs or TIFFs the colourspace is already baked in and you should view them in the same colourspace.
Steve: I can use a calibrated screen for sRGB, Adobe RGB or in the monitor's Native (full). So if I understand you correctly, I should use sRGB for editing in Lightroom for the internet. However, my monitor NEC PA242W is a new wide gamut unit for photography. Should I use sRGB or Native (Full)? What about when I edit in and for older type printers which I believe I have (Canon ip4600)?
Should I use Native (Full) if I intend to have an outside lab print it or should I check with them to see what they want?