Weddingbee boards

My vote would be for South America - I'd go to Argentina and maybe Brazil.  In Buenos Aires (Arg) you have one of the world's most romantic cities (I haven't been yet but I've done lots of research into it as it's going to be my next big holiday) and it would be an awesome place for a honeymoon.  You can also head south to see the glaciers of Patagonia, and sample some of the world's best wine and beef regions in the world, also in Argentina.  If you head north towards Uruguay or Brazil, you'll have some beautiful beaches to relax on as well.  October is heading into summertime in South America so the weather shouldn't be too bad.   

Depending how much time you have, you could start in Buenos Aires and cross the continent through Bolivia, ending up in Peru, or you could do a loop of sorts and end up in Santiago, Chile.  

If you really want an adventure, I'd maybe look into some alone time in BA to start, and then hook up with a small group tour (G Adventures or Intrepid Travel) as you will get to visit a lot more places and have a more authentic experience as you can get off the beaten path.   I've been on several tours with couples on their honeymoon and they've always seemed to love it...and most of them have tacked on a few days at either end of the trip for just themselves.  Just something to think about.

As for Thailand - it can be expensive to fly there but once you're there, everything else is dirt cheap.   I've been there twice, once to go from Bangkok north to Chiang Mai to do a hilltribe trek (pretty awesome) and once to go from Bangkok south through Khao Sok National Park and hitting the islands of Koh Samui and Koh Tao (also awesome).  

ETA:  Somehow I forgot the part in your original post about wanting a relaxing holiday - in that case, maybe scrap South America and go to Thailand instead.  Although I would second a PP's suggestion of going to Borneo instead  - much less touristy, home to the organgutans, beautiful beaches, and a gorgeous place to be! 

@nataliegrace90:   Bring lots and lots of books and magazines; also, book a flight on a good airlines.  Thai Airways is lovely, as is Malaysian Airways, Singapore, and Cathay Pacific.  Fly one of the Asian airlines instead of the American airlines and you will have a better experience.  Not that I'm trying to take business away from American companies but their long distance planes just don't measure up to the Asian airlines in terms of comfort, food, and entertainment systems. 

I fly all the time between Australia and Chicago - a 29 hour journey minimum, sometimes longer if the connections aren't great.  I always bring my Kindle, a paperback book, a couple of magazines, my iPod (with games in addition to the music), and lots of snacks, although I ususally don't end up eating most of them.  It's not the end of the world and the time goes by fairly quickly.  It's most definitely worth the inconvenience of losing a day and spending 24+ hrs on an airplane to explore parts of the world you would otherwise never see.

Oh and water.... drink lots and lots of water!  Yes, you will get up to use the loo all the time but you won't get as dehydrated which goes a long way towards keeping jet lag at bay and helping you feel like a normal human being when you get off the plane.

ETA:  You might lose two days when you fly west to Asia.  I always lose 2 days when I fly back to Australia.  The Australian flights leave late in the evening on a Monday (for example) and arrive in the morning on a Wednesday in Australia.  Just an fyi.