Not sure if this is still true, but last December (2020), they gave a card out and said to call the number to say that you want to see an open house. However, when I called the number and wanted to visit AKL, they said to just talk to security and they will let you in. We did that and they let us in. We also did the same thing for OKW and Saratoga Springs. The only one they said you might need a reservation for was Riviera. However, we just took the skyliner there, and lo and behold, they were able to help us.
Here is a list of open house rooms (without OKW and SS as those became available at a later date):
https://dvcfan.com/2020/08/12/a-new-kind-of-dvc-preview/
If you are doing brunch at BW, then you can visit BW, Beach Club, and Riviera. In addition, if you can get to one of the monorail resorts, or the TTC (e.g., bite the bullet and pay $25 for parking), you can easily check out the monorail resorts (e.g., BLT, Poly, GF). Note that those are the most difficult to get to. BLT, especially. My guess is because so many people try to park there for free and then go to the MK. We've been questioned even when we had dinner reservations at the Contemporary. However, it is unlikely you'll have issues with OKW, Saratoga Springs, or AKL due to the vast size of the resorts and the large amount of parking.
Can't say how difficult or easy it is to get in at Wilderness Lodge as we were staying there. Copper Creek has the cabin, but Boulder Ridge was the only resort without a room available for previews. If you are visiting one of the monorail resorts, you can take the monorail to the MK, and then take the ferry over to Wilderness Lodge.