When I started flying I was encouraged by my instructor to buy a rather nice leather logbook cover. Black (deep navy blue and maroon I recall were also available), it was well made and tastefully embossed with 'Personal Flying Logbook' or similar on the front cover and inset in light, subtle smallish font gold type. I liked it. My current logbook is the UK CAP407 type for which I've not seen a similar cover (not that I'm looking). Those I have noticed for the larger commercial sized logbooks appear to have a big set of gold wings and pilot logbook in big F/O letters on the front a bit like those gash licence covers you can get - presumably so an innocent punter doesn't pick it up off the clubhouse bar thinking it's a menu? I knew someone who used to cover their logbooks with expired laminated charts cut to size (but he was ex-public school).