Jim,
Hope I don't muddy the water too much but you might want to look at Aperture since you are using Macs. I admit I am not that up to speed on LR but one of the advantages that seems to be mentioned from other users of both programs is that Aperture gives you the ability to have referenced images in your library. What this means is you can have access to all your images on your laptop via the Aperture library through thumbnails (you have some control on the quality of thumbnails as well). A referenced file could be stored on a hard drive, CD, DVD, etc. Of course to edit the image you need to mount the device or media where the file is located.
You could copy the Aperture library to all your computers and have the images stored on a network drive (or something like the DROBO
http://www.apertureprofessional.com/...ad.php?t=10435). Then no mater what computer you were on as long as it was connected to the network where your images were kept you would be able to edit them. I do know that I cannot run Aperture simultaneously on more than one machine connected to the network as it detects another copy running.