2 week holiday holiday destination on a budget

Sulawesi or Sumatra ....if you liked Indonesia.

Belize and CR are good shouts..not dirt cheap but reasonablly priced.

How about Guatemala for the culture and adventure and a few days in Belize for the wildlife and the sea?

"a mix of beaches, culture, wildlife and adventure."

That's easy. Miami.

Just read your post, and I would recommend Vietnam! We spent 3 weeks in Vietnam travelling from Ho Chi Min to Hanoi, it was amazing! And like the places you have already been it has so many different things to offer, amazing food, beaches, history and people! Laos is also equally as amazing! We are thinking of booking a 3 week trip to Sri Lanka, would you recommend it? I don't know anyone who has been so an feedback or information you could offer would be great? I wasn't sure if 3 weeks would be too long? And we like to get around on trains and busses etc with local people, however a lot of people talk about getting a car and driver, is this necessary?
If you want any more specific info on Vietnam or Laos give me a shout! Cheers