Lease a much smaller building with some good parking and put in "hotel space" desks, wifi, healthy snacks. Keep it as lean as possible and keep the contracts to 1 or 2 years. This gives people a chance to mentor in person and for people that need socialization to do so. The smaller building should have some meeting and training rooms and also some private/quiet rooms so people can focus. There should be a few sound-proof booths for phone calls to keep distractions to a minimum. Ensure that all levels of management have bi-annual training to make the best of remote-work and to ensure their employees are productive, healthy and happy.
Like a library or a gym, but for your mind.
And if there's already a gym, bingo!
This is for a full building, but you can also do something social for many smaller places.
Unless your company outright owns the building, your lease contract will usually have pretty severe restrictions about what you can or cannot do with the space.
If your company outright owns the building, chances are that your management may already be looking into selling it but can't find a buyer at a price they like.