I have the BJ City Mini and double City Mini GT. The GT version is a little easier to push, has better shocks and the seats have a little more padding. Otherwise, they're very similar. I've seen the BOB at Buy Buy Baby and thought it was too big/bulky for my normal activities.
As for handle height, the GT says adjustable but it won't be that much different for two tall people. The highest adjustment setting on the GT matches the height of the normal, non-adjustable handle on the City Mini. If one adult was significantly shorter, the adjustable handle might be a deciding factor.
I just took the double to Silver Dollar City a few weekends ago, and thought it was great. The suspension on the GT does seem better than the regular BJCM and goes over bumps in your path easily. SDC doesn't have the crowd density problem that DLR has, but they have tons of HILLS! The GT easily went up the hill with ~60 lbs worth of children/stuff inside. Plus, after a few learning attempts, I can now pretty easily take the double through normal doorways, 36" or larger. I will definitely be taking the GT with us to the park, mall, zoo, SDC, etc until DD decides strollers are no longer fun.
I am going to fly to LAX with one of the BJ strollers, just not sure if the double is worth it at the airport. The BJCM is SO easy to collapse, lift up high if needed, pop the wheels off for X-ray machines, etc. I'm not sure the double will be as airport friendly. If I decide to only use the single BJCM, I am going to rent from a second BJCM from City Strollers in Anaheim. I already have my rental reservation made...but I am way indecisive and might do the double instead!
Whew - sorry for the rambling reply (you can tell I've had a similar debate going on about stroller choices) and good luck with your stroller!