I did a few calculations for a story on how many people would plausibly fit in a dome.
Assuming: (1) a dome radius of around 1 km; (2) a slightly 'cut-down' hemisphere (there must be a word for this but I don't know it); (3) space-filling vertically to fill; (4) 50% of the space filled by industrial or communal uses (parks, transport &c); and (5) a space allocation per family/couple roughly equivalent to a two-up, two-down terrace house on average (this felt conservative to me: higher classes might have more, but would form a relatively small proportion of the total population, lower classes would almost certainly have less). I reckoned you could accommodate several million people in a single dome. This rather surprised me. (Maybe I did my sums wrong.)
I agree with those who have postulated living like this would tend to induce a cryptic style of speech. The idea felt to me like my London commuting years....
Tavia