In the UK "thee" is also often used for emphasis. For example ... of all "thuh" great cities in the world, New York is "THEE" place to go for its buzz and lively atmosphere. Hope that helps.

Thuh. This is the type of thing which varies from region, person, country, etc. For the most part people in my area say thuh. I rarely hear thee. When I do, its primarily used to express sarcasm. Example: Who are you talking to? Just Ryan. THEE Ryan Smith??? This would basically mean that Ryan Smith is arrogant.

To add to my other point: the pronunciation with a full /i/ vowel is normally only used before a word beginning in a vowel or for special emphasis. When New Yorkers refer to Manhattan as “the City,” they are not being emphatic — it’s taken for granted (tacitly understood) that Manhattan is the only city in the universe, so the usual, reduced pronunciation of “the” is used. ;)

If you want the full effect, you'll want to say "duh" -- as in /dəsɪt̬i/. ;)