I may be uninformed, but I am not aware of any bike in the Specialized line-up where you can have your saddle adjusted for efficient pedaling and still be able to stop with your feet on the ground while in the saddle, so I think with your requirements, the Electra line is your best bet.

Weight isn't a big issue on rail trail rides, but it could help very slightly to have a lighter bike for any minor up hill sections. In looking at the Electra site, I would consider one of the Townies, Ticinos or Lofts. Find out which is lighter, and by how much, and if there is a price difference whether it is worth it to you. Also test riding each (if you can) would be helpful to determine what feels best for you.

For rail trail riding, one of the 7 or 8 speed models should be fine, if you do any riding with more climbing, you might want to step up to 21 speeds or higher.