dunno how i should start this, but this is just my small advice
form your collection, i can see that you have invested a lot in your gear and few are the top of the line especially the 17-55 and 85mm, and you planning to get a wider angle lens

IMO, 16-35mm on 7D is wasted as 17-55 is far more practical and it has the L lens quality just without the Red ring, so dun waste your money for the 16-35mm if you planning to use it on APS-C..quite no point to gain the L and extra 1mm and paying another few thousand grand

besides, you suggested the 10-22mm lens, which is superb for landscape, i had tried before for months and it do give me gooding picture and perspective, but i am not a wide angle freak, so 10-22 does not suite me very well...quite a hard to frame picture unless you shooting landscape or getting very close to the subject and give a big head look, but i vote for this lens over the 16-35mm la

but it all depend on you, and see what is your shooting habit, there must be a reason why you grab the 28mm and 85mm, if for me i will take the 28mm for street photography and 85mm for dedicated portraiture work, plus the f1.8 is a big plus to me...in my case, i will keep these two lens, just trying to give some suggestion and solve your problem without breaking the bank
Cheers!

This post has been edited by lamjunrong: Aug 11 2013, 12:40 PM

Siggy 8-16 is not a fisheye lens, is a UWA lens with visible distortion when come to 8mm end; focusing is slow when come to UWA lens, but siggy one is bit slower, and narrower aperture

which lens you bought first? 17-55 or the 28mm? when purchasing the next lens, try not to overlap the zoom range, for example you have the 18-55mm kit lens and then you go and buy a 17-55mm which is dunno how many times the pricing is...then end up you either leave a lens in the corner or would not bother to pick up both of the lens, as you just stick to the prime lens...

for me size and factor is one thing, so i prefer prime, this said by many photog, 'zooming prime lens using my foot'....so i rather leave the 17-55 at home, as its heavy...one more thing is we tend to buy lens to cover every angle that is possible, ranging from 8mm to 300mm or more, imagine how many lens are there, unless you are seriously no problem on budget and you are working or having a studio...

in the end, there are many advantage of prime lens over zoom lens such as aperture, sharpness, smaller size, better color and less distortion; but there is only one advantage of zoom lens over prime lens...it zooms...

so pick your weapon

This post has been edited by lamjunrong: Aug 11 2013, 04:44 PM