I think SE released a size chart before the release of 1.0, can't find it though.

Anyway, here's what I think:

Lalafell: 2-3 feet
Miqo'te: 4-5 feet
Midlander: 5-6 feet
Highlander: 5'6" - 6'6"
Roe: 6 - 7 feet
Elezen: 6 - 7 feet

Roe and Elezen are really close, but I think a Roe may be slightly taller by a few inches.

*Does the Summon Ferne dance*

Not official, but those would be my guesses using a Midlander as an average human height.