Any tips on train travel from Bangkok to Chiang Mai? I'd appreciate details.?

Though I have been to Bangkok several times, Ive never taken the train. So I'd be grateful for details from Bangkok's train station to Chiang Mai. How much, how long does the journey take? Are there night trains? Thanks.

Yes, there are overnight trains - take 2nd class sleeper (fan or AC is up to you, but you don't need AC during the cold season), but do not take 3rd class (it will kill you back/buttocks) and do not take 1st class (then you better go on a low-cost airline).

Below link has a lot of detailed info

State Railway of Thailand's website at http://www.railway.co.th/english/index.asp
has information on routes/timetables.