"So what would be your "best route to Bangkok" this way? 2 nights hotel, 2,5 days ride."
2 and 1/2 days?
Heading via Mae Sot. Maybe try and get to Mae Sariang first night. The next take time from Mae Saraiang top Mae Sot. Its worth it. It is one of the most beautiful roads in Asia.... Slow in any case obviously since it follows the Burma border and the Salween. It’s a beauty. Then stay one night in Mae Sot or Tak depending on how early you started.
Last day.... Just welly it down the freeway from Tak to BKK.
Heading the other way. First night in Lampang , Phistanulok, or even Sukhothai (get up at dawn for the temples). Next day head east on Highway 12 to Lomsak, Petchebun, area..... You then have options of how much of that that area you can explore. National park and good resorts and hills around Lomsak area at the top of Highway 21 and heading on east up towards Loei, Dansai and Chiang Khan region. DON’T stay a night in Petchebun unless you can help it. Main hotel doubles up as trucker-hooker-karaoke and is loud until 4am and it’s a shitpit. Stay in Lomsak or resort in the hills nearby. Next day head down 21. That veers west off heading west to the junction around Saraaburi area (I don't have a map to hand now... But that area), but you can carry on due south (from Chai Badan) on small roads towards area west of pakchong through Muak Lek. This takes you on small roads through rice paddies and hills. You can then stay one night in a resort on the Pakchong-Kaho Yai road (2090 I think). Beautiful and peaceful and in the hills... Well nearly. Through Khai Yai early morning, across to Prachinburi, Chaechingsao and on to BKK via the 304.....
One can get from Laos border and Udon to BKK pretty much small roads all the way (bar about 200km south of Lomsak and Petchebun) through hills and countryside.... It’s the nicest way to go, but way outside of your way from CM. I did this a couple of times in May and it takes out the north to south slog. Really nice rides.
Another way, if you are interested in Thai history is go via Sukhothai one night and Ayuthaya the next with a look at the temples, one set each morning. Boring rides, but great sightseeing.
Be aware that getting through Bangkok at the end of a long drive is a nightmare…. I always stay one night in Ayuthaya, Kanburi, Nakhon Pathom, Pakchong or Prachinbuuri before taking on the beast…. It can be three or four housr through the city depending on traffic and where you are heading…. If you staying up north of town try and enter via Bang Pha In etc. If Sukhumvit he then the 304....
And if this is your first time riding in TL.... Take it SLOW at first... Roads are unpredictable. If its not, then you know that anyway ;-)
Cheers
Dan