This loop hits Thailand's three classic budget-travel zones — capital, north, and islands — without the schedule feeling rushed, using the overnight train instead of pricier internal flights for the longest leg.
Days 1–3: Bangkok
Land, adjust, and cover the Grand Palace, Wat Pho, and a night at a rooftop bar that isn't marked up for tourists (ask your hostel staff, not a review site). Guesthouses near Banglamphu run $10–15 a night.
Days 4–6: Chiang Mai
Take the overnight sleeper train from Bangkok ($20–28 for a second-class berth) rather than a $40+ flight — you save money and a hotel night in one move. Use these three days for the Old City temples and a day trip to Doi Suthep.
Days 7–10: Islands
Fly budget carrier from Chiang Mai to Krabi or Koh Samui ($35–55 if booked a few weeks out) rather than backtracking through Bangkok by land, which eats a full extra day. Four days is enough for one or two islands without feeling like a layover.
Takeaway: The overnight train between Bangkok and Chiang Mai is the single best value move in this loop — book the sleeper berth a week or more ahead, since it sells out.