I always figured a 10 bay garage to be about perfect, although 2 are for maintanence.
My cars would be:
1972 Stingray convertible, big rat motor, metalflake blue with a white leather interior.
1936 Ford, running as a '50's stocker, with a flathead and no fenders.
1974 Bronco, with a pickup cab, and tall narrow tires, orange.
1966 Thunderbird, with the 428, white leather interior and fender skirts, painted metalflake baby blue.
1968 Mercedes 280, though I would have a few modifications:

2003 Thunderbird, flat baby-blue.
T-bucket, nuff said.
2005 Ford F350 with a service body, including a welder, air compressor, torch and enough tool boxes to git 'er done.