FlyerTalk Evangelist
Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: BA Silver, TK E+, AA PP, Hyatt Globalist, Marriott LT Plat, Hilton Diamond
Posts: 13,033
By the book... no elite benefits unless booked in your name.
In practice hotels might still let you stay in the same room and/or give you breakfast.
It's also worth valuing the points and elite nights you would earn, benefits you would be guaranteeing, etc. against the cost of paying for that fourth night. i.e. all 8 nights in your name.