I don't have partners but, if I did, I would never do it virtually, even if the other partner was in CA. You are so close, it's a no-brainer. Partners need to know each other, bond, learn each other's idiosyncrasies, and respect each other and I see no other way than in-person. Heck, I've thought of flying out to CO to have a retreat with my staff to better bond with them. I have found virtual is great for one-off quick meetings with staff but I feel like I need some in-person time with them too.