Hi I'm 29, and although I havn't quite made my mind up just yet the Rockies is definatly in my top 3 places to go this year and June would be when I would be wanting to go too, it being the mountains, I don't want it toooo cold. I absolutly love mountains, and beautiful scenery and its somewhere I've been wanting to go since I was at school.
I did my first trip with Just You last October to California and Hawaii and it was amazing. Before that I'd never been away by myself before or even travelled outside of Europe. Like you I was worried about being the youngest, and as it turned out I was by about 15ish years. However it didn't matter at all, everyone was really friendly and I chatted to alot of different people of all ages. I really didn't feel like I was the odd one out in any way. I'm also really shy around meeting new people but after 2 weeks together everyone became more like friends than strangers. So I would say really don't worry about the ages, if there's somewhere you want to go then you should take the chance. This is a really good way to see the world if you're on your own but don't want to go by yourself as you're never left on your own unless you choose to be.
I'll definatly be using Just You again this year, my only problem being making my mind up where to go. The travel bug has got me and there's so many places I want to visit now :)
Hayley