As it was already said, it is hard to tell without knowing more, however, I am going to try to answer keeping a general view, and understanding from your post that you shoot street photography, as you say you do a lot of photography in the street.
I know lots of people are going to disagree with me, but I greatly prefer prime over zoom lens.
I am a big fan of Henri Cartier-Bresson (who can be consider as one of the most (if not the most) influential and talented street photographer); whenever he was shooting for himself, he would use a 50mm, so his camera can really become an "extension of his eye". I personally think that he was right in doing so.
Prime can have much bigger maximal aperture than zoom; I personally don't know a zoom lens that is faster than f/2.8, but know a lot of f/1.4 prime. Bigger aperture can not only be useful in low light situation, but gives you more option in term of depth of field control. Everybody love bokeh 
Also, they tend to be sharper or/and cheaper, however, this is not always the case.
Of course, having access to multiple focal length is extremely useful; zoom lens are far more practical that prime in that regard. However, I tend to think that limiting yourself to only a few focal length gives you the opportunity to master them. I personally view photography much more as an art form than a business form (this is really just my opinion), so the usefulness isn't all that important compare to the possibility of growing as an artist.
Ultimately, the most important thing to keep in mind is that what really matters is which lens you prefer, even though I am sure that you will get some awesome advices from this forum. In street photography, I think the best focal are 50mm, 35mm, 85mm and 135mm. However, everybody as their own view and their own preference, depending on their style and their view of what is photography in itself. This is, for me, an awesome thing; people having different view and preference is one of the reason why, after nearly 200 years, there is still lots of great and unique photos taken nowadays.
In summary (sorry for the long text, I hope it was not too boring!), if I was you, it would use that money on a few fast prime. The 24-70 II is about 2300$, so that leaves enough money for some good lens! If you are into manual lens, Zeiss are close to top (a poor man choice would be Samyang, which are extremely good for the price!). If you prefer lens build in a more modern view, I heard great things about Sigma 35mm and saw great things about Sigma 50mm f/1.4. Also, the Canon 85mm f/1.8 is one of the best values IMO in Canon's lens.
Thank you, it wasn't boring at all 
Very informative indeed +1
This weekend i'm taking a trip to Santa Cruz with my girlfriend. Mostly not going to shoot Street Photography but mostly just shots of the gal and me. Mostly shots of her.
I'm also going to order tomorrow some lenses and do 2 day shipping on them so they can arrive early.
Now i've never tried the mark 2 zoom but for $2,000 do you think it's better then most of the primes out there?
I found the 35mm L lens for about a Grand and might be able to buy an 85mm.
Just don't know, I want bokeh shots but then again a zoom might be more useful.
Happy you liked it!
I have no personal experience with the 24-70mm II; I heard it was a fantastic lens in term of sharpness, AF, etc. This zoom range covers what is normally all the most "all around' focal length, so it is far from being useless. However, from what I understand, it seems that you are starting in photography; although I'm a bit of a "sharpness junkie" myself, investing that kind of money in a single lens might not be your best bet. If you are not an already experience photograph, I doubt you are going to take better picture with a 24-70 II than with a 24-70 I or a 24-105. Since they cost 2-3 x less (depending if you buy used or not) than the 24-70 II, it could leave you with enough money to find yourself lens to complete your needs. For instance, you could go with a 24-70 I or 24-105 for a walk around lens and a 85mm f/1.8 for some awesome bokehlicious portrait of your girlfriend!
Even then, you would still have save about 800$; it is close to the price of a Sigma 35mm f/1.4!
I think you should not buy to much lens right at the beginning though, 2 or 3 maximum. It is important to know what you are going to be shooting and where what you already have is laking before spending money on lens you might not need all that much.
zoom... gives u flexibility....
I won't be having a tripod with me. I think I might just go with the canon 24-105 since it has IS.
I know I just recommended the 24-105, however, I feel I should tell you that IS, as much as it can be useful in some situation, is not always necessary. It is going to be useful on long focal length and in low light situation. If you plan to do night photography, you are probably going to need a tripod anyway; no IS can help you having clean 5s shoot! During daylight, you won't need it that much neither. However, it can be really nice to have for low light and interior shoots, considering also that the 24-105 as a maximum aperture of f/4.
I feel this lens could be a great choice for a standard zoom, especially if bought used (great idea TexPhoto)!:)
