I just did the mansions and lunch and the cliff walk with my sil this past tuesday!
We did the 5 manions ticket for $31 per person. You can pick which 5 you want to visit (with the exception of 1 that isn't part of that package, it didn't look good anyways!). We did the Breakers, walked on the cliff walk from there until the next "exit", walked up a LONG dirt road to the main street, saw the Marble House, walked back to RoseCliff (this one has a/c on the first floor....soooo nice! it was about 95 degrees in the other houses, lol). Then we took the trolley ($1.75 per person for one ride) back to the Breakers where we had parked. Drove back to town for lunch. We ate at the Red Parrot, it was very yummy and affordable! It dosen't have outdoor seating but we were seriously melting and didn't want to sit outside anyways.
After lunch we went back and saw the Elms and finally the Bell house. Skip the Bell house, it's "under renovations" and completely empty!! It does have beautiful woodwork but again....sooo hot and with nothing to look at boring!!
We did a TON of walking. My sil runs marathons and I walk a lot and we were both feeling it by 5pm (we arrived around 10:15 at the first house). Make sure the kids are prepared! They don't allow any picture taking inside the mansions either which bummed me out....they are beautiful!!
Message me if you have any questions!!