In rough order of price and less emphasis on exact focal lengths, I consider these to be the "wide guys."
~$500 Canon 28mm/1.8
~$900 Sigma 35mm/1.4 - hard to argue with the reviews and price
~$1300 Canon 35mm/1.4L
~$1400 Canon 16-35mm/2.8L - not as "fast" as the primes, but versatile and fairly light
~$1500 Canon 24mm/1.4L - my favorite wide prime
(I don't keep track of lens revision numbers; just look at the latest versions.)
You can look at the newer lenses I call the "slow primes" like the 24mm/2.8 IS, but I'm skeptical about their usefulness. Being able to hand-hold the shot isn't always the most important thing - sometimes you need wider aperture and faster shutter speeds in low light to prevent subject motion blur. I'm guessing those slower stabilized lenses are better suited for video.
Looking for a fast lens, mainly for indoor(with low light) use. It will be used in family events, indoor parties at night and its usage will range from single to group portraits.
My favorite is definitely the 24mm/1.4L, but I don't think it's the best focal length for portraits, except for large groups. 35mm, 50mm, or 85mm works better for individuals. Given your intended usage, I have to agree with the recommendations for the new Sigma 35mm/1.4. It's fast, sharp, affordable, wide on the 5D3, and normal on the 60D.
And definitely sell your thrifty fifty and get its USM brother. Nothing wrong with the 50mm/1.8 but when you start reaching its limits, it's time to upgrade.