Exclude with robots.txt? Re-direct? Leave alone?

I need to bring 4 URLs back into 1 main site.

[TrumanTiger]

es 4 very different products (widgets 1-4). They had an existing site at widgetmaker.com

Over the past year, we’ve broken their 4 products, one at a time, into separate sites and placed them on their own URL for the time being.
widget1.com
widget2.com
widget3.com
widget4.com

These searate sites are now all indexed, ranking well and have a few outside links to them. Having completed all the product sites and corporate information, we’ve recently brought everything back into one site, like so:

widgetmaker.com/widget1/
widgetmaker.com/widget2/
widgetmaker.com/widget3/
widgetmaker.com/widget4/

Now that we’re getting fresh tags on files within the new folders (/widget1/), how long should I let the individual product sites (widget1.com, etc.) sit out there before doing what I can to make those sites disappear from the SEs?

Should I: 1. Exclude spiders using robots.txt and leave the product sites up awhile? 2. Take down the product sites and put custom 404s that have a link to the corresponding folder on the widgetmaker.com site? 3. Or take down the product sites entirely and re-direct to the proper folder on the main site?

[WebGuerrilla]

4. 301 each individual page of the product sites to its new location on the corporate site.