As I learned from your posts, Ankola - Udupi - Mangalore route is dangerous.
Further, I wont advice to travel through NH17 (old number) from Kasargode to Ernakulam just to save some distance.
You cannot reach Alleppey in 5 - 6 hours.
Road is narrow and with notorious buses racing against each other and doing rash driving.
Also sachin mentioned that he don't want that coastal route.
We have an excellent highway (NH4) and extra distance via Salem is only less than 200 km but can compensated by the road condition.
I have travelled through this route till Ernakulam last year (June 2011) and again planning to do in this April.
Its not dangerous buddy, I told him to be cautious while driving.
I didn't see the one he mentioned not to visit through Coastal areas.
And my intention is to visit maximum places on the way.
He can visit Udupi, Krishna Temple, Murdeshwar etc.
I meant he can reach in 5-6 hours from Thallaserry, i.e. after Kannur-Muzhapilangad.
These are the places of interest that can be covered in single trip.
My view is to break the trip into several slots and visit all the nearby places, and not to cover in one go.
Take adequate rest and do a long drive.
In Kerala KTDC hotels are the best and inexpensive.
In Kannur we stayed at Tamarind Hotel of KTDC.