^ I'm not sure about Hawaii, although I'm sure it's probably a good location to grow weed, but I believe the Mediterranean or most places closer to the equator are usually up there amongst the best.
I'm not sure I agree with your LED comment, given the state of LED grow light technology now (it's appalling, to be frank), but I agree with the sentiment that lighting technology has improved a lot. I think, however, that unless they can come up with a lighting technology that gives you a lot more light output of a semi-decent spectrum from a lot less power input, growing weed indoors with lights is going to become a lot less desirable (granted, there will always be a need/demand for commercial growers or those that can't or won't grow outdoors). Energy prices are going through the roof right now - so much so that it's getting to the stage where I just can't afford to grow indoors much at all really.
The south of the UK gives a climate good enough to grow extremely good weed. The only problem is that a lot of strains keep flowering into the autumn when it gets colder and more rainy, causing issues with mould. However there are strains that have been developed which are 'semi-autoflowering'. Unlike autoflowering strains they start flowering in about June when the number of hours of light starts to decrease and they finish in time before you get major issues with bud rot etc. The strains I bought were from Female Seeds - Purple Maroc, Maroc and I also bought their Purple Power which had been off the market for a while, but has now been improved. I've not grown this type of weed before so it should make for an interesting grow. The good thing about our climate in the south of the UK is that we have the gulf stream, which moderates our climate, making growing anything from tomatoes to weed much easier. If the climate in the South of the UK is good enough to grow the sort of grapes they grow in France to make wine, then weed will definitely grow generally without any major issues.
Shown below are Purple maroc and Purple Power in that order.
edit: when I said I think LED lighting technology is appalling, I meant for growing plants specifically.