He's worth his many 1000s of Baht just for entertainment value. He's far scarier than this older "monk days" photo suggests. Have you every met a Thai rapper?
From past experience I know it gets VERY VERY hot and progressivley more humid after the end of February. Last time I was there end of feb / early march it was 40 degrees Celcius in Chiang Mai. Trail riding can be quite demanding, and if it is very hot, then it gets quite uncomfortable.
My standard tour costs £750 GB pounds, (plus whatever your own flights cost to and from Thailand). This normally runs from a Saturday (leaving from London Heathrow Airport) and returning on a Wednesday, 1.5 weeks later. This is 12 days, including the travelling days - which in reality is 9 full days and 10 nights in Thailand.
So my standard tour for £750 GBP is 10 nights / 9 full days in Thailand. The price includes a Thai guide, me, a 4x4 support vehicle & driver, all accommodation and motorcycle hire.
You need more money for your bike fuel and your drinks and meals, BUT THIS IS NOT EXPENSIVE. We normally operate a "kitty" system for meals and drinks in Thailand. This january / february our kitty totalled £109 GBP each. This was all meals, nearly all beers and all bike fuel. Obviously, when in Thailand, we deal in Thai Baht.
The kitty for the Nov / Dec 06 trip only came to £60 GBP per head (about four top-ups of 1000 Baht each). This covered bike fuel, park entrance fees, meals and drinks. Amazing.
Spending an extra few days in Bangkok is a good idea - worth doing. You can do this at the beginning or end of your trip, to make your holiday into a full 2 weeks. I would suggest the END of your trip. Why? Because BKK is hotter than Chaing Mai, so 1.5 weeks in the North, where it is a little cooler, will get you used to the heat gradually. Also you will get used to the food and learn a few Thai words - useful for when you're alone in BKK. Finally shopping is one thing you do in BKK, and you don't want to buy things at the beginning and have to store them or carry them round for the whole trip.
A few days in BKK will add a little extra cost to your trip. For example, if you flew from CNX (Chiang Mai) to BKK on the Wednesday, and spent 3 nights (2.5 full days) there (flying home to on Saturday, for example), it would cost approximately £100 extra each. This would be staying at a very comfortable 4+ star hotel (in twin rooms - i.e two per room) in an ideal location. I've stayed here a few times before. It's not far from the river, right next to the snake farm, and is dead opposite Patpong, which you may have heard, has rather "interesting" nightlife shall we say, as well as it's famous night markets.
NOTE - I don't do Bangkok anymore personally. I come home after the trail riding bit. I've been to BKK several times. Been there, seen it, done all that. It is worth seeing if you've never been, but I no longer feel the desire to go there every trip! However, you don't need me there to hold your hand. I can suggest an excellent and convenient hotel, provide ideas on places to see and give you the run-down on do's and don'ts whilst there.
Just another thought.......
I always need a driver for these Thailand tours, see one of small sections above.
If you have a friend (male or female) who can drive a 4x4, nearly always on the road, (unless we need it for rescue purposes!) and who wants a cheaper holiday, let me know. They still have a great time -we meet up every night, and often lunchtimes as well. They see most things we see, do the same things on the rest days, and generally have a great time, whilst supporting the group and carrying our bags. The small jeep we use can actually carry two people plus all our bags. We use a much larger 4x4 pick-up sometimes.
All ideas worth considering. If you want to follow up further, it would be worth discussing on the phone. Thailand is quite a different culture, and this trip is the most adventurous one I offer. It's not third world, but one the other hand, accommodation / rules of the road etc. are not what you'd find in Europe.
I consider my French Alps trips and my Thailand trips to be my best tours.