I would not settle for 18-55. Plastic cheap, 3.5-5.6, I don't believe worth the time of day to even use the lens. yes it does cover the range but would you rather have a better piece of glass? I figured out very early(as well as you) that primes are the way to go. Zoom is helpful but primes make the difference. Radical idea, sell all your glass you have (maybe not the 50 or upgrade to the 1.4) and take that money with the money you have now and set yourself up with some good primes?
Yes you won't have the versatility of going to 300mm right off the bat but in most situations you can zoom with your feet. I own two L lenses myself and I can say I almost use my 85mm 1.8 more than those lenses. My setup consists of 16-35, sig 50mm 1.4, 85mm 1.8, and canon 135 f/2. The 85 is a top performer out of my bag followed by the 135. Since I'm shooting on a 5d i don't have quite the reach with the 135 but it beats out the 70-200 in my opinion (weight, size, cost, flashiness). I rented the 35 1.4L over the summer and was in love, covered great angles and was sharp as all get out.
The 135 I bought for 900 was a great purchase and the 35 1.4L would be my next lens. I've been debating myself to sell my 16-35 for it. I'm not quite sure what I"m going to do with it, I wanted to give my opinion on the matter. I hope you can see my point of view on it. Rent before you buy or at least get hands on. It'll put everything into perspective.
