[TYPO3-english] Best practice -- multiple domains with localization

[Tony Lush]

Is there a best practice for implementing a family of web sites in 
TYPO3? They will have similar looks, perhaps with shared HTML templates, 
but different style sheets. Several will be localized.

Domain1.tlc  English and German
Domain2.tlc  English
Domain2.tlc  English and Spanish
Domain4.tlc  English, German and Polish
Domain5.tlc  English
Domain6.tlc  English

I am wondering if there is any advantage to having one install, using 
TYPO3's ability to have multiple domains on one page tree, or separate 
domains and page trees.

Best regards -- Tony