Do you plan on finishing other space in the basement at all? If so, what other spaces do you have planned?
If the theater is the only space you are going to finish, I might mirror it under the great room. If you want to finish other rooms, it might be best to have it off to the side perhaps under the kitchen/breakfast nook, or under the master bed/bath?
7.4.4 Theater Room: JVC-RS500, Silver Ticket AT 2.35:1 142”, Onkyo RZ830, Anthem PVA-7, Panasonic UB420, Apple TV 4K, JBL Studio 530’s, 4 - 15" DIY Sealed Subs
3.1 Living Room: Samsung 64” F8500 Plasma, Anthem MRX 300, Dynaudio Audience 52’s, Dynaudio Audience 122C, NHT SubOne, Roku Express (2019)