The CRX usually only runs when it's nice out. It's in a heated garage now, so there's no problem starting it...in winter she'll just idle in the driveway, no more salt for that car.
The Civic will just get driven once she's started. If it's really cold out (below 15 F) I'll usually let her idle just long enough to scrape off the ice or snow that's built up since the last time she was run.
The Rovers? Dunno, don't have them running yet...heh.
Bogatyr