yeh english is so limited in translating the meaning of arabic...
if you want to translate samaawaat properly, i'd rather translate it as "ultimate heights" or something like that.. samaa maens "upper limit" "height"... And it's definately not sky because sky is 'sahaab'.. and in none of the hadiths pertaining to isra n maraj did the prophet mention the word sky..
and its not like the prophet used sama instead of sky all his life, because int he punishment of thamud and '3ad it was a 'sahaab' of punishment (thunder n stuff) that came along.. not a 'samaa' of punishment..
From the incident of the father n the daughter its also evident that sama was more than jsut sky.. she was referring to the "boundary" lol.
salamz