I currently have two bikes:

'14 Fuji Sportif 1.3: Upgraded to 105 FD/RD/Shifters for cleaner lines and shifting. Also toyed around with tires (looking up some Compass Bon Jon Pass 35c) for commuting. Also great for gravel and endurance riding, all I need is just to change the tires currently, actually seeking out a different wheelset to make the change easier.

'12 Fuji SST 2.0 UDi2: Strictly for training and local fast rides.

On the radar:

Definitely a cheap beater for campus beat downs
A proper gravel bike (Jamis Renegade, CAADX, and GT Grade are on the short list)
Another, better quality endurance bike (like a Specialized Roubaix)
A chopper/cruiser bike (brother-in-law builds custom rigs and is in that scene pretty heavily)
A mountain bike (have a few rides under my legs, but haven't researched enough to narrow down a choice)
Cargo bike... possibly.
Also... the gravel/CX bike would most likely act as a bikepacking platform, that or the MTB.

I'd also look at different wheelsets for the bikes which could give them better versatility and possibly relinquish the need for another bike altogether.

All things to lust after... it's great to have a wife who only rolls her eyes at my hobby when I'm not looking.