I agree with the others - about a 7-8 minute walk to City Walk from RPR, about 12-15 minute walk to US. We usually opted to walk when we were going to IOA & the boat when going to US.
When we were there in mid-June they were sometimes only running 1 boat, so the line & the wait got kind of long & it was definitely quicker to walk. When they were running 2 boats, the wait was much less.