Luss-
North from Bangkok is dull which every way you slice it. A suggestion would be to take R1 out of Bangkok to Saraburi.
At Saraburi, take R21 to Petchabun.
Just north of Petchabun is Khao Kho, where there are some spectacular roads and views if you havn''t stopped there before, plenty of hotels and decent food there, worth a look.
From Khao Kho, take R203 north to the Laos border, Thai towns called Na Haeo and Pak Man are right on the Laos border, you can use the road signs to these places if it becomes confusing.
From there find your way west onto R1268 and put Nan in as a WP destination.
From Nan, you know about R 1148, one of the best roads in Asia and the way to Spicy from there.
Russ if you've got time this is the fun route back from Nan to Chiang Mai
