I think I am reading the OP in that they have/had some EF-S lenses that covered a number of focal lengths. What lenses were they, and we can point you to a few equivalent tools.
The idea of getting some vintage lenses to use is mostly misguided. They don't have the coatings and current technology to make use of what the 6D can offer - and if nothing else it will find any and every flaw. The reason to use vintage glass is to go fully manual or to achieve a 'look' out of camera. If this doesn't match up with what you want, stick to what you can afford in the current line up.
It's hard to look at the same focal length day in and out, but there are a number of cheap zoom's that can scratch an itch. Based on what I saw on your blog, a 17-40mm f4, 24-105mm f4 and/or 70-200mm f4 lens should be in your future - cheap even in euro's and you will sell again when upgrading later on for a net-zero cost. You've spent over 1,600 Euro's on a camera, and it's only as good as the glass you put in front of it.
I've got nothing against primes. I have four of them. But, for someone with a new body and one $100 lens, I feel that a good walk-around zoom is the most economical beginning point. I've done manual focus and primes for 30 years or more, mostly because that was the only choice I had when I began taking photographs. I'm am so over that.
But, if you are talking primes, I can't imagine not having a 24 or 28 mm wide angle and a 100 or 135 mm short telephoto at a minimum. Just those two lenses will set you back more than the street price of a 24-105. I just think it is bad advice to suggest someone load up on a bunch of outdated manual focus primes when they can get a perfectly functional all purpose zoom that will help them learn the craft first.
As you have correctly guessed, i had a T2i with 3 lenses: 18-55mm/3.5-5.6, 50mm/1.8 II, Sigma 10-20mm/4-5.6. The kit lens and the Sigma were sold, and now the T2i with the Tamron 17-50mm/2.8 is for my family to use. I got the 6D a month ago, purposedly bought without the kit lens. F/4 is kinda slow, i knew i wouldn't want to trade the fast aperture with the zoom. I took pictures with the nifty fifty and i discovered i don't like the focal length much. I always feel i'm leaving something outside the frame, and head and shoulders portraits show a not so pleasing distortion.
Renting gear is not an option here in Italy. So it came to my mind that maybe buying cheap vintage lenses, using them for a while, and then reselling, was a cheap way to test many different focal lengths. I have no real interest in vintage lenses.
With the budget i set for my next lens purchase (1500€), i could get the 24/1.4 L, or the Sigma 35/1.4 and the 24/2.8. How did you choose your primes before buying them? Did you always start having a zoom first, and then got the primes based on the experience with that particular focal length?
Vintage wine will help you find the way.
How come it didn't came to my mind? This one is even cheaper than a Red Ring! http://www.ebay.it/itm/Sassicaia-1985-/281234074652?pt=Vini&hash=item417adb6c1c&_uhb=1
Re: Will vintage lenses help me find the way?
No, but L lenses will, no matter which one you pick. Beware of the L addiction, though... symptoms include red rings, improved upper body strength, and the occasional marital troubles...
Yeah, the plan was to test the focal lengths, and then getting Red Rings in those i liked the most.