Have the Canon 7d... I have the EF 50mm F1.2L and the EF-S 17-55mm 3.5-5.6.

I think im over analysing my next purchase. I cant decide because, I cant quite wrap my head around the different variables... For example, I have a 50mm lens, yes but its closer to an 85mm lens because of the APS-C (1.6x). If someone can confirm if the EF-S is designed for the APS-C Sensor that would be cool, meaning that i have a lens that is a 17-55mm or if it is actually subject to the magnification as well.

I think i want something to fill the gaps. I know the biggest decision I have to make is do I get a Telephoto or a Wide Angle, I also know that i want another L Series lens.

I have been taking quite a few gig pics and have found that im having to back up quite alot with the 50mm F1.2... so I thought that the 24-105mm F4L would be good because it kind of appeals to both wants (tele and wide), but then I forgot about the 1.6x which would make it a 38-168mm and its a F4... Will I find that im still backing up? Will I find that its too dark and that im compensating with ISO?

Is there anything else that I should be considering? I have thought about getting something like the 17-40mm F4L but I cant quite justify it because i have the EF-S lens. The other thing I would like to get is a Fisheye but again Im not sure how often I would use it (that and which one do i get). Or am I being to narrow? Should I be looking at an after-market lens (Sigma, Tamron, Tonkina etc).

My maximum expenditure is about $2k-$2.5K, absolute maximum. I would (as im sure most people would agree) like NOT to spend that much.

Any advise would be appreciated.

P.S. I have madly typed this out between calls at work. Please forgive me if there are spelling/grammar/random typos. Im rushing.