We've been to OKW twice, once with a car, once without. It is a really beautiful but very huge resort. The first time, without the car, we were very close to a bus stop and a quiet pool so it was a good location. I found the bus service to be very good. But the walk to Olivia's, which we also thought was good, was a bit much. In the morning, when we were rested, it was no big deal. But later in the day after walking FOREVER the last thing we wanted to do was treck across the resort. Thus the car the next time. That time we were close to the hospitality house and probably didn't need it but I loved having it. The rooms are very nice and quite large and I found the CMs there to be wonderful. We have also stayed at the Boardwalk twice and we love it there too but they are really different. One is quiet and relaxing, the other is lively and in the middle of everything. If you plan to eat out a lot, the variety of restaurants on the boardwalk is nice. If you enjoy the Downtown Disney area, the boat ride over from OKW is fun and relaxing. If you have older kids, they might enjoy the pool at the Boardwalk more. If not, the pool at OKW is very pretty.
Good luck with your decision. I'm sure you'll love whichever place you choose. But if you pick OKW and don't plan to have a car, give your feet a break and ask to be put near the Hospitality House.