24L - 50L - 135L were my choice. Very expensive and took time to get but well worth it.
28mm 1.8 - 50mm 1.4 - 100mm f/2. Much more reasonable setup.
That's what I've got: 28mm 1.8 - 50mm 1.8 - 100mm f/2. All nice lenses, the 100 is great for sports. Although I have to say I never use the 28 anymore since I got the 17-40 a few months ago.
Usually I switch between the 17-40 and the 50. Since I've got the cheapy 1.8 this new rumored 50 sounds very interesting to me!
But to answer your question: if you do a lot of landscape/wide-angle then I wouldn't go for primes. The comfort of being able to zoom beats shallower DOF.
I do hope your not excluding the 17mm & 24mm T&S.