Thailand forum

I got lots of questionsand have spent many hours finding answers on this wonderful site. Ill give someinfo and dive right into my questions.

4 weeks(september 1st -october 1st)
budget of about 3000-4000USD after airfare.
flying into BKk
traveling alone 25yo male

Rough itinerary:
2-3 days inbangkok/surrounding areas.
12-16 days in northernthailand IE chiang mai and other provs
10-12days in southernthailand IE islands and coastal provs

Weather
questions based mostlyaround the time in southern thailand. im from western washington state in theus.. where its a temperate rainforest by definition. 200+ days of rain a year.mostly just drizzles for days on end.. so im not afraid of rain but idefinitely want to spend some time soaking up the sun, scuba diving, snorkelingetc. can you guys recommend a couple islands to spend the time on? im notafraid of crowds, noise, and alcohol, but I would like to see all the iconicbeauty and some of the not so known spots. I also had read that rain can causecancellations in tours up north, any validity to that?

Trekking/whitewaterrafting.
this part is the mostimportant to me. i want to trek through thick jungles, climb through caves andwaterfalls, and raft whitewater rapids. im in excellent shape so that shouldntbe an issue. im definately interested in seeing elephants.. but shy away fromthe fake "zoo" like shows. ive read through reviews and researchedthe cities people recommend but im just curious if anyone has first handexperience with some amazing guides/tours. This is also the portion of the tripthat I have the least issues sending more money on.

Traveling.
first and foremost illbeing flying from the northern thailand to the southern islands.
id also like toexperience motorcycling through the forested hills of northen thailand. im anexperienced rider here in the states and mostly wanted to know if they have anybigger bikes available.. im used to 600cc+ crotchrockets and have never riddena scooter/moped. is it feasible in the monsoon season? And also I saw that thata ticket from Bangkok to chaing mai is pretty cheap. Is it worth it? Or should Itake the overnite train?

and one other randomquestion, would doing an ankor wat trip be a smart idea before heading north?im adament about experiencing the north and south.and figure i can hit it upnext trip if im lacking in time. im sure ill have more questions later

thanks!!