I tend to go through bottom brackets quickly because I am about 215lbs and had a serious injury on my right leg a few years ago. I push much harder with my left leg so that after 3-5k miles i wear out my BB. I currently have SM-bb70 (part of the SLX group set) on my Bruce Gordon BLT.
My rookie questions are: Are bottom bracket sizes standard? In other words. When looking for a replacement do I need to measure the size of my BB 1st? Do you have a recommendation for a long lasting BB? I don't mind paying a bit more for a BB if it will last longer.

Thanks