The closest buildings to the “action” (and the hardest to get) is Building 62, with 63 and 64 close behind.
Buildings 11 through 16 are right across from Hospitality House, but they were among the first built at OKW - which means that there is only one door to the bathroom and that is through the master bedroom. This isn’t a problem if you’ve rented a 2 bedroom suite though, as the second bedroom of course has it’s own bathroom. If you’re renting a one bedroom, that means anyone using the bathroom has to walk through the master bedroom. Not a huge problem, but one you may want to consider. Further away from the “action”, but one of the prettiest locations right on the river are Buildings 45 and 46. Buildings 23 through 27 are pretty close to Hospitality House too.