24-70 + 70-200 is a convenient setting, but is not the only possible one. IMO, you cover more subjects with a 24-70mm (real wide angle to short tele) than with a 70-200 (short tele to long tele).
You could as well consider other (cheaper) combinations :
- 24-70mm f2.8 (or f4 IS) + 135 f2 (keep your 50mm)
- 24-105mm f4 IS + 200mm f2.8 (keep you 50mm)
- 16-35mm f2.8 (or 17-40mm f4) + your 50mm + 70-200mm f2.8
All these lenses are good, but you must define what focal range will be the most useful for you. If you do not know yet, try by any mean to rent or borrow these lenses or some equivalent ones to make up your mind before you spend $2000+.
Have fun with your new toy(s)