Last time I checked, Geocities didn't support HTTP keep-alive. They do however support gzip compression, which wget doesn't support. Also, as you noticed, including "Googlebot" in the User-Agent works around the bw limit.
Did you archive regional versions (de.geocities.com, etc.) too? I see that (any-subdomain).reocities.com currently is just an alias for reocities.com. I have ~ 12 GB of archived data from de.geocities.com (couldn't find more links and didn't have the time later on), saved in the same format as wget (mtime set according to Last-Modified header etc.) if you are interested.