I feel your pain there, brother, and yes, we are all brothers in the All-Seeing-Eyes of Grimm. We all have our lead mountains, we have studied the philosophy of cork and so on and so forth. I am not here to preach to the choir...
Part of being in this hobby is finding what you can do or make that works in the life-space that you are able to set aside for it. I don't know how many of us have tremendous storage areas for large-scale projects and huge terrain and building archives, but I know I have a good amount of space that is taken up with clutter and half finished projects...enough of that.
You have, admittedly, thousands of beautifully painted miniatures, try and figure out what you can build to make a setting for the ones you like to use the most, want to use more or are just completely in love with. For instance, pulp gaming can take you damn near anywhere on this planet or others.
1. Some sort of African village...huts and so forth and so on...maybe a colonial office even.
2. Some kind of crowded marketplace in the Near East...think Cairo from Raiders of the Lost Ark...and buy tons of cork board
3. Pulp city ....with a waterfront or without...make the terrain in such a way that you can either have a board for each or figure out a way to make things interchangeable
My point is that if you make things just a bit generic enough, you can use them for different time periods and get more terrain time out of less building time. Sometimes, you really just need a Tibetan Temple and it is going to look like exactly that, and that is fine, but identify what you think you need and go at it a building or terrain bit at a time.
UncleRhino