The Netherlands has 'legal' access to marijuarna, mushrooms and various 'herbal' highs such as salvia, peyote and hawaiian woodrose seeds.
Belgium and Luxembourg have similarly extremely tolerant attitudes to the smoking of pot but legality isn't changed. Don't go anywhere near Scandinavia. Spain and Portugal (all legal?!?! I REALLY doubt that...would violate international obligations) also pretty bloody easy with the drugs, and of course, if you make the run over to Ibiza you have as many pills as you can afford ($ will become a serious issue).
If your thinking Africa look to Morrocco...its pretty arabic but friendly as hell to foreigners once u get away from the ports and the hash is apparently the best in the world and forms such a substantial part of the economy that government makes almost no effort to stop it.
If you want to go to Tibet, pot grows wild on the side of the road. Difficult to get caught...
Athens has certain shops about the place (I have no idea if they sell, I think they do), where guys sit outside with those massive ass bong things (as tall as a pygmy) and smoke hash on the street. Never saw any outside of Athens but drugs are widely tolerated in Greece. Unfortunately if you do get odne look to spend 20 years in a Greek prison - no distinction between supply and possession.
Canada and parts of Australia are pretty much no to everything except pot which is decriminalised. There are other jurisdictions where its decriminalised as well but I cbf thinking of them. Its also being carefully considered in the U.K., which if it happens will be your ideal destination. I dont know about the other parts but Liberty Caps grow wild in Scotland and are fuckign EVERYWHERE. London is impossibly easy to find pills at and you will pay between 3 and 4 pounds for very top quality shit (AU bout 10 bucks). You can also buy crack on the streets and mingle amongst the thousands upon thousands of destitute crackheads.
If this doesnt sound liek you, it is my learned opinion that w/i the next few years NZ will also decriminalise and we also have a few legal options. On the downside everythign else is horribly expensive and sometimes hard to get.
I dont know shit about South America or the rest of Asia, but if you get caught smoking pot in Japan, you go to jail for around 10 years, and other jurisdictions are similiary strict...not a good idea. South America is also pretty bloody dangerous and is economically extremely unstable.
Your best bet is this: Either set up in London and stay there. You can get everythign cheap as hell and the biggest task will be not becoming a crackhead...Theres a big BIG au/nz community over tehre...try find 'the church' if you can, and even newspapers keeping u up to date with whats going on in Aus...Hell I think theres even a pie shop now!!!!!
OR
Go to western continental Europe, don't live in Amsterdam - its dangerous, depressing and extremely touristy. You'll kill yourself after a few months...either go and live somewhere in a small Dutch town and reap the identical benefits of Amsterdam (no, amsterdam isnt a country...)...cheap legal pot, mushrooms and crazy alternative highs, with a completely and utterly sane setting (the netherlands is a model of drug legalisation success outside amsterdam) or use Amsterdam as your stock up base, and move around a few different countries. The security on trains is pretty incredibly piss poor, and i dont think stuff liek mushrooms have a distinct smell for any sniffer dogs that might randomly waltz past (this is very very rare, and if you get a night train, non-existent). DO NOT, however, try to ship on planes or across the chunnel. Chemical detectors etc are used and you WILL get snapped. Cannot stress that enough. Ferry = not sure. I took about 5 grams of dope across on a ferry to London but thats your own risk...I shat my pants at the procedure there.
To summarise: The Netherlands = total freedom, but also freedom to spill out into other countries due to lax border countrols. Amsterdam itself is somethign of a depressing shithole and once you've seen the sights you will want to move on. 6000 black guys saying 'charlie, ex' as you walk past starts to fuck with your head on mushrooms...