Tamron makes good products... but if you are considering resale at all, I think Canon holds its value better. IF you know of anyone who might be eligible for the Tamron educational rebate... you might be able to save a little more. Do a google search for it... education program... something or other. EPP.
I hear the 24-70 is a great lens, but it is just heavy as balls (iron ones I presume). I think this is one of the best value lenses available in the L series... and that is partly because there are so many made as they are included as a kit lens with the 5dmk ii and iii.
Definitely agree on the resale of the Tamron. The $1200 price tag of it is keeping me away from it. Will definitely pull the trigger if it hits $1000. In the meantime, my 17-40L will do for now...