You have a BD lounge in T1 dom and T1 int. As a BA gold you can use the terraces if you want on any occasion anyway, so try and compare! You can take a guest in when flying BD (as with BA), which you cannot do under the Open Doors when flying BD- so you have the best of both worlds.

BD have business lounge and diamond club lounge within the business lounge. Have a look at the sticky at the top of the BD thread.