You know where you wanna go!!
You ever been to Thailand during Songkran?
I've traveled to England, Thailand, Malaysia and Singapore by myself. My first trip was England solo which wasn't bad since English was no problem. SE Asia was interesting on the fly but I had no one to bother me which made it an experience I will never forget. I loved every minute of it and stayed in places most wouldn't enjoy. I also met amazing people along the way and had no one to look out for or make sure the other person is having a good time. I'm more adventurous than most so I sometimes feel held back bc I know who I'm traveling with isn't as open to new things.
Going solo can be great - and sometimes lonely too. It's best to include things that incerase the chances of meeting people, as that is what it is all about really.
Stay in hostels.
Hostels are no longer "youth hostels". Anyone can stay. In Europe especially they are open to all. But best to stay in non-official hostels, i.e. independent hostels. They are still excellent but dont have crazy rules about what time u need to get up etc.
Bring your smartphone.
There are an increasing number of sites that cater for solo travellers. TravBuddy and Wandermates.com are two I have used (this is me on Wandermates http://www.wandermates.com/profileview.php?profileuserid=9 :) No site is perfect but by spreading yoruself around u can increase the chances of meeting someone.
Go on group activities.
Go on a 2 or 3 day trip to do scuba, climbing, cycling etc. THat way to get to meet likeminded people and have fun. I have done it a lot and it s s agreat way tp break the ice and meet a few buddies. Plus, it is short enough that u are not bpgged dow. Alternatively book a longer session with someone like Exodus.co.uk or Explore. I have done trps with them in Turkey and MOrocco and they were both turely excellent!
Onsen are freaking awesome. Spent a few of my days in Japan in the mountains above Nagano alternating between eating, sleeping, exploring and relaxing in the onsen. Sitting in the hot springs with snow all around is something that must be experienced. They are all over Japan; Tokyo, for instance, has many onsen that are like clubs/gyms/spas what have you. But traveling to 'take the onsen' in various places is a very Japanese holiday. They are typically sex segregated, and one always bathes nude (unless in a touristy place), so sitting with naked Japanese guys is de riguer. It is the way of things and not uncomfortable. I have not taken the onsen with a sumo, admittedly. Though we were able to reserve a private outdoor onsen so that my gf and I could enjoy it together. It is a very relaxing experience.
I have never experienced onsen 'in the wild' as it were; natural pools and mountain springs that one hikes to get to. That would be intense. Would love to do that sometime. HRoi, you should totally Google image search 'onsen' -- see some of these things.
I mean, I am ridiculously introverted, too. But there are modes in which I prefer to have social interaction at home, and I do them when I am away, too. (disclaimer, I have often traveled alone, but not out of the country). I do, basically, just walk alone from place to place and am generally happy with that since no one is annoying me. I do a lot of photography, which I also prefer to do solo, so it is no big deal. If I were gone for a long time, I probably would need to find some english-speaking people just so that I could have a normal conversation.
Change of plans. Gonna end up in Miami instead since I'm trying to do some business while on vacation as well.
The bright side is that I'm saving money since I'll be staying in my Aunt's empty house.
The NYC trip is a definite must in the near future though, especially since I did so much planning for it already.