Lens indecision

I've been thinking of reviewing which lenses I use. My cheap Tamron 18-250 that I picked up is alright but seldom does it provide images quite as notably sharp as those taken on either my Nikon 5mm prime or my Tokina 11-16mm. At least part of this is the lack of vibration reduction provided by that model, ever more important at the long end of things.

Swapping it for a Nikon equivalent gives me the options of 55mm or 70mm to 200mm or 300mm. Either way, I'm losing the 18-55 range. From that perspective, Nikon's 18-105mm appeals but them I'm weighed down with four lenses and that certainly doesn't appeal:

Tokina 11-16mm
Nikon 18-105mm
Nikon 50mm prime
Nikon 70-300mm

That's a heavy bag.