N+1 Maybe....

[Norm]

Stick some knobbly tyres and a child seat on the back and use it for weekend rides and maybe winter commuter then buy a Secteur/Tricross and use that as the main bike.

Damned good choices.

And there's you answer, Vike. Whatever bike you get, it has to be different to the current stable. Briefly, mine are:
#1 Viking steel road bike I've had for 30 years - incomparable to anything else
#2 Giant Coldrock rigid MTB I've had for 20 years - mudguards, rack and pink frame make it the perfect bike to leave in town but it's light and fun to ride.
#3 Giant Talon hardtail MTB - for off-road trips
#4 Spesh Secteur road bike - for road trips
#5 Spesh Tricross - the most fabulous mix of abilities, light, strong, built for tarmac and mud/grass

So, whatever bike you have now, think about what you want to get next, what it does differently and there is your justification.