I actually think we should go back to hydrogen filled airships. They're the perfect platform for electric flight free of greenhouse gas emissions. Just load it up with batteries and put some range extending photovoltaics on top. Sure, batteries are heavy, but that's not an issue if relatively cheap hydrogen is used instead of helium for lift. We have the technology to use hydrogen safety so it really seems like the way to go.
I thought airships were retired after the Hindenburg incident. I'd heard they were working on helium filled ones to avert future similar disasters, but didn't realise they were in general use yet. I live in London and have never seen one.